JP2018048871A - BASIC COLOR-CHANGING pH INDICATOR MONOMER AND pH INDICATOR COPOLYMER - Google Patents
BASIC COLOR-CHANGING pH INDICATOR MONOMER AND pH INDICATOR COPOLYMER Download PDFInfo
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本発明は塩基性色調変化型ｐＨ指示用モノマー及びｐＨ指示用共重合体に関し，とくに塩基性範囲で色調変化するｐＨ指示用モノマー及びそれを用いたｐＨ指示用共重合体に関する。 The present invention relates to a basic color-changeable pH-indicating monomer and a pH-indicating copolymer, and more particularly to a pH-indicating monomer that changes color in a basic range and a pH-indicating copolymer using the same.
河川・湖沼，空気・大気，地質等の環境モニタリングにおいて，例えば所定地点におけるｐＨを長期にわたり継続的にモニタリングすること（ｐＨモニタリング）を求められることがある。従来から一般的なｐＨ測定法は，液体（水溶液等）に接触させたｐＨ指示薬の色調変化を見る比色分析と，液体に浸漬した電極の起電力を計測する電気化学分析である。しかし，従来の比色分析は，紙等に含浸させた低分子のｐＨ指示薬（リトマス試験紙等）を用いるものであり，液体中に長期間浸漬し続けるとｐＨ指示薬が溶出してしまう問題点がある。また電気化学分析は，電極の頻繁なメンテナンスが欠かせないものであり，液体中に電極を長期間浸漬し続けると表面に異物が析出・付着するおそれがあるので，無人化が基本となるような長期のｐＨモニタリングに適用することは難しい。 In environmental monitoring of rivers / lakes, air / air, geology, etc., for example, it may be required to continuously monitor pH at a predetermined point over a long period of time (pH monitoring). Conventionally, a general pH measurement method is a colorimetric analysis in which a color change of a pH indicator brought into contact with a liquid (aqueous solution or the like) is observed, and an electrochemical analysis in which an electromotive force of an electrode immersed in the liquid is measured. However, the conventional colorimetric analysis uses a low molecular pH indicator (such as litmus paper) impregnated in paper or the like, and there is a problem in that the pH indicator is eluted if it is immersed in a liquid for a long period of time. . Electrochemical analysis requires frequent maintenance of the electrode. If the electrode is immersed in a liquid for a long period of time, foreign matter may be deposited on the surface. It is difficult to apply to long-term pH monitoring.
これに対し，ｐＨ指示部位及び重合性部位を有する単量体成分（ｐＨ指示用モノマー）と電気的中性部位及び重合性部位を有する単量体成分（非イオン性モノマー）とを共重合させた色調変化型の高分子材料をｐＨモニタリングに用いることが提案されている（特許文献１及び２参照）。例えば特許文献１は，（２）式に示すように，メチルイエローとメタクリル酸とを反応して得られたジメチルアミノアゾベンゼンアクリレート（ＡＡＢＡＡ）をｐＨ指示用モノマーとし，非イオン性モノマーであるＮ−イソプロピルアクリルアミド（ＮＩＰＡＡｍ）と共重合させた色調変化型共重合体を開示している。
In contrast, a monomer component having a pH indicating site and a polymerizable site (pH indicating monomer) is copolymerized with a monomer component having an electrically neutral site and a polymerizable site (nonionic monomer). It has been proposed to use a color change type polymer material for pH monitoring (see Patent Documents 1 and 2). For example, in Patent Document 1, as shown in the formula (2), dimethylaminoazobenzene acrylate (AABAA) obtained by reacting methyl yellow and methacrylic acid is used as a pH-indicating monomer, and N— which is a nonionic monomer. A color change copolymer copolymerized with isopropylacrylamide (NIPAAm) is disclosed.
（２）式のような色調変化型共重合体は，ｐＨ指示部が強固な共有結合で高分子鎖に担持されており，液体に長期間浸漬してもｐＨ指示部が溶出するおそれがない。また必要に応じて，（２）式のようにイオン性部位及び重合性部位を有する単量体成分（イオン性モノマー）を含めて共重合させ，ｐＨ指示用モノマーが色調変化するｐＨ領域を塩基性側又は酸性側へシフトさせることにより，共重合体の色調変化領域をｐＨ指示用モノマーに固有の変色域から移動させ，色調変化領域を制御することが可能である。 (2) In the color tone changing copolymer as shown in the formula, the pH indicator is supported on the polymer chain by a strong covalent bond, and there is no possibility that the pH indicator will be eluted even if immersed in a liquid for a long period of time. . Further, if necessary, copolymerization is carried out including a monomer component (ionic monomer) having an ionic part and a polymerizable part as shown in the formula (2), and the pH region in which the pH indicator monomer changes color tone is changed to a base. By shifting to the acid side or the acid side, the color tone change region of the copolymer can be moved from the color change region specific to the pH indicating monomer, and the color tone change region can be controlled.
更に，（２）式のような色調変化型共重合体をｐＨモニタリングに適用するため，ｐＨ指示用モノマーの発色からｐＨ値を精度よく測定する方法が提案されている（特許文献３参照）。例えば特許文献３は，ｐＨ指示用モノマーの発色を白色点Ｏが中央に配置された色度図Ｍ（図７（Ａ）参照）上にプロットしてその白色点Ｏが中心の極座標上の発色点Ｃの偏角Ｄを検出し，ｐＨ値の異なる複数の標本に接触させた共重合体の発色点Ｃ１，Ｃ２，……の偏角Ｄ１，Ｄ２，……と各標本のｐＨ値との関係式Ｆ１（図７（Ｂ）及び（Ｃ）参照）を予め設定しておき，測定対象の液体に浸漬させた共重合体の発色から発色点Ｃの偏角Ｄを検出し，その発色点Ｃの偏角Ｄと関係式Ｆ１とから測定対象の液体のｐＨ値を求める方法を開示している。 Furthermore, in order to apply the color tone changing copolymer represented by the formula (2) to pH monitoring, a method of measuring the pH value with accuracy from the color development of the pH indicating monomer has been proposed (see Patent Document 3). For example, in Patent Document 3, the color development of a pH indicating monomer is plotted on a chromaticity diagram M (see FIG. 7A) in which a white point O is arranged at the center, and the color development on a polar coordinate centered on the white point O. The deviation angle D of point C is detected, and the deviation angles D1, D2,... Of the color development points C1, C2,. The relational expression F1 (see FIGS. 7B and 7C) is set in advance, and the deviation angle D of the color development point C is detected from the color development of the copolymer immersed in the liquid to be measured. A method for obtaining the pH value of the liquid to be measured from the deviation angle D of C and the relational expression F1 is disclosed.
図７（Ａ）は色度図Ｍの一例であるＣＩＥｘｙ色度図Ｍ１を示している。この色度図Ｍ１には，表色上の３原色の刺激値（Ｘ，Ｙ，Ｚ）に基づき全ての色が２つの数値（ｘ，ｙ）＝（Ｘ／（Ｘ＋Ｙ＋Ｚ），Ｙ／（Ｘ＋Ｙ＋Ｚ））として表現されており，ｐＨ指示用モノマーの発色を２つの数値の発色点Ｃ（ｘ，ｙ）としてプロットすることができる。また，ほぼ中央に白色点Ｏが配置されており，その白色点Ｏを中心とする極座標系を想定することにより，全ての色の数値（ｘ，ｙ）を動径ｒ及び偏角Ｄに変換することができる。図７（Ｂ）はｐＨ値の異なる複数の標本に接触させた色調変化型共重合体の発色点Ｃ１，Ｃ２，……が白色点Ｏを中心として弧を描くように並んでいることを示しており，図７（Ｃ）はそのような各発色点Ｃ１，Ｃ２，……のｐＨ値と偏角Ｄとの関係式Ｆ１の一例を示している。特許文献３は，偏角ＤからｐＨ値を精度よく推定するため，（Ａ）式のようなロジスティックモデル（ロジスティック曲線）で近似した関係式Ｆ１を用いることが有効であることを開示している。
Ｄ＝α／（１＋β・ｅｘｐ（−γ・ｐＨ）） ………………………（Ａ）
FIG. 7A shows a CIExy chromaticity diagram M1, which is an example of the chromaticity diagram M. In this chromaticity diagram M1, all colors are represented by two numerical values (x, y) = (X / (X + Y + Z), Y / (X + Y + Z) based on the stimulus values (X, Y, Z) of the three primary colors on the color. )), And the color development of the pH indicating monomer can be plotted as the two color development points C (x, y). In addition, a white point O is arranged almost at the center, and by assuming a polar coordinate system centered on the white point O, numerical values (x, y) of all colors are converted into a radius vector r and a declination angle D. can do. FIG. 7B shows that the color development points C1, C2,... Of the color change type copolymers brought into contact with a plurality of specimens having different pH values are arranged in an arc around the white point O. FIG. 7C shows an example of a relational expression F1 between the pH value of each of the coloring points C1, C2,. Patent Document 3 discloses that it is effective to use the relational expression F1 approximated by a logistic model (logistic curve) such as the expression (A) in order to accurately estimate the pH value from the declination angle D. .
D = α / (1 + β · exp (−γ · pH)) ……………………… (A)
上述した（２）式のような色調変化型共重合体を用いると共に，その発色から色度図Ｍ１上の偏角Ｄを介してｐＨ値を求める図７のような測定方法を適用することにより，長期間にわたる継続的な環境中のｐＨモニタリングを実現することが期待できる。しかし，特許文献１の開示するＡＡＢＡＡをｐＨ指示用モノマーとする共重合体は，比較的狭い酸性範囲で色調変化を示すものであり（ｐＨ１．０〜４．０程度，図７（Ｃ）参照），イオン性モノマーを含めて共重合させることで色調変化領域を多少シフトさせることは可能であるものの，測定できるｐＨ範囲が限定的である。環境モニタリング等では酸性から塩基性にわたる広い範囲のｐＨの継続的な測定を求められる場合があり，そのような広範囲のｐＨモニタリングを色調変化型共重合体によって実現するためには，ＡＡＢＡＡのような酸性範囲で色調変化するｐＨ指示用モノマーだけでなく，塩基性範囲で色調変化するようなｐＨ指示用モノマーの開発が必要である。 By using a color tone changing type copolymer like the above-mentioned formula (2) and applying a measuring method as shown in FIG. 7 for obtaining the pH value from the color development through the deviation angle D on the chromaticity diagram M1. , It can be expected to realize continuous pH monitoring in the environment over a long period of time. However, the copolymer having AABAA as a pH indicating monomer disclosed in Patent Document 1 exhibits a change in color tone in a relatively narrow acidic range (about pH 1.0 to 4.0, see FIG. 7C). ), It is possible to slightly shift the color change region by copolymerization including the ionic monomer, but the measurable pH range is limited. In environmental monitoring, etc., continuous measurement of a wide range of pH ranging from acidic to basic may be required, and in order to realize such a wide range of pH monitoring with a color-change-type copolymer, It is necessary to develop not only a pH indicator monomer that changes color in the acidic range but also a pH indicator monomer that changes color in the basic range.
そこで本発明の目的は，塩基性範囲で色調変化するｐＨ指示用モノマー及びそれを用いた色調変化型共重合体を提供することにある。 Accordingly, an object of the present invention is to provide a pH indicator monomer that changes color tone in a basic range and a color tone change type copolymer using the same.
本発明者は，（３）式のようにｐＨ７〜９の領域で黄色から青色へ色調変化を示すαナフトールフタレインに注目した。αナフトールフタレイン自体は分子内に重合性基を持たないため高分子化できないが，αナフトールフタレインに重合性基を導入すれば，塩基性範囲で色調変化するαナフトールフタレインをｐＨ指示部位とするｐＨ指示用モノマーとすることが期待できる。ただし，一般的に色調変化を示す低分子のｐＨ指示薬は重合性基を導入すると類似の色調変化を示さなくなることが多く，このため従来は紙等に含浸させて低分子のまま用いることが主流であった。本発明者は，重合性基を導入しても低分子の場合と類似の色調変化を示すαナフトールフタレインの置換部位の研究開発の結果，本発明の完成に至ったものである。
The present inventor has paid attention to α-naphtholphthalein that exhibits a color tone change from yellow to blue in the range of pH 7 to 9 as expressed by the formula (3). Although α-naphtholphthalein itself does not have a polymerizable group in the molecule, it cannot be polymerized, but if a polymerizable group is introduced into α-naphtholphthalein, α-naphtholphthalein that changes color tone in the basic range is converted into a pH-indicating site. It can be expected to be a pH indicating monomer. However, in general, low molecular pH indicators that exhibit a change in color tone often do not show a similar change in color tone when a polymerizable group is introduced. Met. The present inventor has completed the present invention as a result of research and development on a substitution site of α-naphtholphthalein which exhibits a color change similar to that of a low molecular weight even when a polymerizable group is introduced.
本発明による塩基性色調変化型ｐＨ指示用モノマーは，式（１）で表されるαナフトールフタレインのイソベンゾフラン縮合環の６位又は５位に重合性基を結合してなり，塩基性ｐＨ領域で色調変化するものである。
The basic color-changing type pH indicating monomer according to the present invention is formed by bonding a polymerizable group to the 6- or 5-position of the isobenzofuran condensed ring of α-naphtholphthalein represented by the formula (1). The color changes in the area.
重合性基は，付加重合性のアクリルロイル基，メタアクリルロイル基，アクリルロイルオキシ基，メタアクリルロイルオキシ基，ビニル基，及び縮合重合性のカルボキシル基，アミノ基，アルデヒド基，環状エーテル基の何れかとすることができる。また，重合性基は，αナフトールフタレインに直接結合するか，又は，アルキレン基，エーテル結合，カルボニル基，−ＣＯ−ＮＨ−の少なくとも一種を介して結合することができる。 Polymerizable groups include addition-polymerizable acryloyl groups, methacryloyl groups, acryloyloxy groups, methacryloyloxy groups, vinyl groups, and condensation-polymerizable carboxyl groups, amino groups, aldehyde groups, and cyclic ether groups. It can be either. The polymerizable group can be directly bonded to α-naphtholphthalein, or can be bonded through at least one of an alkylene group, an ether bond, a carbonyl group, and —CO—NH—.
本発明によるｐＨ指示用共重合体は，上述した式（１）で表されるαナフトールフタレインから誘導されたｐＨ指示用モノマーと，上述した式（２）のような電気的中性部位及び重合性基を含む非イオン性モノマーとを含めて共重合したものである。好ましくは，更にイオン性部位及び重合性基を含むイオン性モノマーを含めて共重合する。 The pH indicating copolymer according to the present invention includes a pH indicating monomer derived from α-naphtholphthalein represented by the above formula (1), an electrically neutral site such as the above formula (2), and It is a copolymerized product including a nonionic monomer containing a polymerizable group. Preferably, the copolymerization is performed including an ionic monomer containing an ionic site and a polymerizable group.
本発明によるｐＨ指示用共重合体には，式（１）で表されるαナフトールフタレインから誘導されたｐＨ指示用モノマーと共に，そのｐＨ指示用モノマーと異なるｐＨ領域で色調変化するｐＨ指示部位及び重合性基を含む第２ｐＨ指示用モノマーを含めて共重合することができる。好ましくは，第２ｐＨ指示用モノマーを，αナフトールフタレインから誘導されたｐＨ指示用モノマーを変色させるｐＨ領域と第２ｐＨ指示用モノマーを変色させるｐＨ領域との中間域において，αナフトールフタレインから誘導されたｐＨ指示用モノマーと近似色であるか又は無色であるものとする。そのような第２ｐＨ指示用モノマーの一例は，式（２）で示すようなジメチルアミノアゾベンゼンアクリレート（ＡＡＢＡＡ）である。 The pH indicating copolymer according to the present invention includes a pH indicating monomer derived from α-naphtholphthalein represented by the formula (1) and a pH indicating site that changes color in a pH region different from that of the pH indicating monomer. And a second pH indicating monomer containing a polymerizable group. Preferably, the second pH-indicating monomer is derived from α-naphtholphthalein in an intermediate range between the pH range in which the pH-indicating monomer derived from α-naphtholphthalein is discolored and the pH region in which the second pH-indicating monomer is discolored. It should be similar in color or colorless to the pH indicating monomer produced. An example of such a second pH indicating monomer is dimethylaminoazobenzene acrylate (AABAA) as shown by formula (2).
本発明による塩基性色調変化型ｐＨ指示用モノマーは，低分子のαナフトールフタレイン（以下，α−ＮＰと表すことがある）と同様に塩基性範囲で類似の色調変化を示すので，電気的中性部位及び重合性部位を有する非イオン性モノマーと共重合させることにより，塩基性範囲で色調変化する高分子材料とすることができる。また，イオン性部位及び重合性部位を有するイオン性モノマーを含めて共重合させることによりに，色調変化するｐＨ領域を塩基性側又は酸性側へシフトさせることもできる。従って，酸性範囲で色調変化を示すＡＡＢＡＡ等のｐＨ指示用モノマーを用いた高分子材料と組み合わせることにより，酸性から塩基性にわたる広い範囲のｐＨモニタリングを実現することができる。また，本発明による塩基性色調変化型ｐＨ指示用モノマーは，酸性範囲で色調変化を示すＡＡＢＡＡ等のｐＨ指示用モノマーを含めて共重合させることにより，酸性から塩基性にわたる広い範囲で色調変化を示す共重合体を合成することも可能である。 Since the basic color-change-type pH indicating monomer according to the present invention exhibits a similar color change in the basic range in the same manner as low-molecular α-naphtholphthalein (hereinafter sometimes referred to as α-NP), By copolymerizing with a nonionic monomer having a neutral site and a polymerizable site, a polymer material that changes color tone in a basic range can be obtained. In addition, by copolymerization including an ionic monomer having an ionic part and a polymerizable part, the pH range in which the color tone changes can be shifted to the basic side or the acidic side. Accordingly, a wide range of pH monitoring from acidic to basic can be realized by combining with a polymer material using a pH indicating monomer such as AABAA that exhibits a color change in the acidic range. In addition, the basic color-changing type pH indicating monomer according to the present invention is copolymerized with a pH-indicating monomer such as AABAA that exhibits a color change in the acidic range, thereby changing the color tone in a wide range from acidic to basic. It is also possible to synthesize the copolymers shown.
以下，添付図面を参照して本発明を実施するための形態及び実施例を説明する。
本発明は，ｐＨ７〜９の塩基性領域において黄色から青色へ色調変化を示す低分子のαナフトールフタレイン（α−ＮＰ）が，イソベンゾフラン縮合環の６位又は５位に重合性基を導入してｐＨ指示用モノマーとした場合にも，ほぼ類似の塩基性領域において，ほぼ類似の色調変化が観察できるとの実験的知見に基づくものである。本発明のｐＨ指示用モノマーを合成する一手順は，α−ＮＰの所定位置にブロモ基（Ｂｒ）を導入し，そのブロモ基を重合性基に置換する方法である。以下，この手順に沿って本発明のｐＨ指示用モノマー及びそれを用いたｐＨ指示用共重合体の合成方法について説明するが，本発明のｐＨ指示用モノマーの合成方法はこれに限定されるわけではなく，例えばブロモ基に代えてヨウ素，塩素その他のハロゲン基を導入したα−ＮＰを出発物質として本発明のｐＨ指示用モノマーを合成することもできる。 In the present invention, a low molecular weight α-naphtholphthalein (α-NP) showing a color change from yellow to blue in a basic region of pH 7 to 9 introduces a polymerizable group at the 6-position or 5-position of the isobenzofuran condensed ring. Even when the pH indicator monomer is used, it is based on experimental knowledge that a substantially similar color change can be observed in a substantially similar basic region. One procedure for synthesizing the pH indicating monomer of the present invention is a method of introducing a bromo group (Br) at a predetermined position of α-NP and substituting the bromo group with a polymerizable group. Hereinafter, the method for synthesizing the pH-indicating monomer of the present invention and the pH-indicating copolymer using the same will be described in accordance with this procedure, but the method for synthesizing the pH-indicating monomer of the present invention is not limited thereto. Instead, for example, the pH-indicating monomer of the present invention can be synthesized using α-NP introduced with iodine, chlorine or other halogen groups in place of the bromo group as a starting material.
（１）α−ＮＰにブロモ基（Ｂｒ）を導入した化合物Ｂｒ−αＮＰの合成
まず，α−ＮＰのイソベンゾフラン縮合環の６位又は５位にブロモ基（Ｂｒ）を導入した化合物（４）を得るため，１．５ｇ（６．０ｍｍｏｌ）の６−ブロモフタル酸無水物と２．０ｇ（１２ｍｍｏｌ）の１−ナフトールとを試験管に入れ，触媒として１０６μリットルの濃硫酸（９５％）を滴下したのち蓋をしてビーカーに入れ，適宜撹拌しながら１７０Ｗの電子レンジで試薬がすべて溶けるまで加熱し，全体が緑色の反応物を得た。
(1) Synthesis of compound Br-αNP in which bromo group (Br) is introduced into α-NP First, compound (4) in which bromo group (Br) is introduced into the 6- or 5-position of the isobenzofuran condensed ring of α-NP. To obtain 1.5 g (6.0 mmol) of 6-bromophthalic anhydride and 2.0 g (12 mmol) of 1-naphthol, and 106 μl of concentrated sulfuric acid (95%) was added dropwise as a catalyst. After that, the lid was put in a beaker and heated with a 170 W microwave oven with proper stirring until all the reagents were dissolved to obtain a green reaction product as a whole.
次いで，試験管内の反応物をクロロホルムで完全に溶かし，クロロホルムと同じ容積の純水を加えて分液操作を行って有機層（クロロホルム層）のみを回収し，回収した有機層に２ｍｏｌ／リットルのＮａＯＨ水溶液を水層が濃い青色になるまで入れてアルカリ性の溶液とした。更に，アルカリ性と酸性とでは反応物の構造が変化して極性が変わるため，溶液に純水を加えて有機層を除き，水層を回収して２ｍｏｌ／リットルの塩酸を加えて酸性の溶液とし，その溶液を濾過して濾紙に残った固体を減圧乾燥し，得られた固体をアセトンに溶かしてサンプル瓶等に回収し，減圧乾燥させた。抽出した化合物をヘキサン：アセトン（６：４）の展開溶媒を用いてカラムクロマトグラフィーにより精製し，Ｒｆ値＝０．３９の橙色の単体化合物（化合物ａ）と，Ｒｆ値＝０．５０の橙色の単体化合物（化合物ｂ）を得た。化合物ａ，ｂはほとんど同じ色であり，異性体であると考えられた。 Next, the reaction product in the test tube is completely dissolved in chloroform, and the same volume of pure water as chloroform is added to carry out a liquid separation operation to recover only the organic layer (chloroform layer). In the recovered organic layer, 2 mol / liter is added. An aqueous NaOH solution was added until the aqueous layer turned dark blue to make an alkaline solution. In addition, since the structure of the reactant changes between alkaline and acidic, the polarity changes, so pure water is added to the solution to remove the organic layer, the aqueous layer is recovered, and 2 mol / liter hydrochloric acid is added to make an acidic solution. The solution was filtered and the solid remaining on the filter paper was dried under reduced pressure. The obtained solid was dissolved in acetone and collected in a sample bottle and dried under reduced pressure. The extracted compound was purified by column chromatography using a developing solvent of hexane: acetone (6: 4), an orange simple compound (compound a) having an Rf value = 0.39, and an orange having an Rf value = 0.50. The simple compound (compound b) was obtained. Compounds a and b were almost the same color and were considered to be isomers.
（２）合成した化合物Ｂｒ−αＮＰの構造の推定及び色調変化の観測
精製により得られた２つの単体化合物ａ，ｂの構造を推定するため，各化合物を重ＤＭＳＯ（ジメチルスルホキシドの６個の水素原子を全て同位体である重水素に置換したＮＭＲ測定用試薬）に溶解させ，それぞれ核磁気共鳴スペクトル（１Ｈ−ＮＭＲ）を求めた。また，比較のため，市販のα−ＮＰの核磁気共鳴スペクトル（１Ｈ−ＮＭＲ）も併せて求めた。得られた各化合物のスペクトルを図１に示す。化合物ａ，ｂとα−ＮＰとの構造上の違いはブロモ基（Ｂｒ）の有無であるが，ブロモ基は１Ｈ−ＮＭＲ上で観測されないため，化合物ａ，ｂにα−ＮＰと類似のシグナルが観測されれば，α−ＮＰにブロモ基が導入された化合物であると推定できる。
(2) Estimation of the structure of the synthesized compound Br-αNP and observation of color change In order to estimate the structures of the two simple compounds a and b obtained by purification, each compound was subjected to heavy DMSO (6 hydrogens of dimethylsulfoxide). An NMR measurement reagent in which all atoms were substituted with isotope deuterium) was dissolved, and a nuclear magnetic resonance spectrum (1H-NMR) was determined. For comparison, a nuclear magnetic resonance spectrum (1H-NMR) of commercially available α-NP was also obtained. The spectrum of each compound obtained is shown in FIG. The structural difference between compounds a and b and α-NP is the presence or absence of a bromo group (Br). However, since the bromo group is not observed on 1H-NMR, signals similar to α-NP are transmitted to compounds a and b. Is observed, it can be presumed that the compound has a bromo group introduced into α-NP.
図１に示す３つの核磁気共鳴スペクトルを比較すると，化合物ａ，ｂは共にα−ＮＰとほぼ同様の位置にシグナルが現れていることが確認できる。これはα−ＮＰにブロモ基が導入された２種類の化合物Ｂｒ−αＮＰ（異性体）が合成されているためと考えられる。具体的には，化合物ａは１０．６ｐｐｍ付近にヒドロキシ基由来のシグナル（ｓｐ１）が観測され，化合物ｂは９．６ｐｐｍ〜１０．６ｐｐｍ付近にヒドロキシ基由来のシグナル（ｓｐ１，ｓｐ２）が観測された。化合物ａはヒドロキシ基が２つあるにも関わらずそのシグナルが１つしか現れていないのは，ブロモ基の位置の違いによる影響で，ヒドロキシ基由来の２つのシグナルが重複しているためと考えられる。 When the three nuclear magnetic resonance spectra shown in FIG. 1 are compared, it can be confirmed that signals appear in both of the compounds a and b at substantially the same position as α-NP. This is considered to be because two types of compounds Br-αNP (isomers) in which a bromo group is introduced into α-NP have been synthesized. Specifically, in compound a, a hydroxy group-derived signal (sp1) is observed around 10.6 ppm, and in compound b, a hydroxy group-derived signal (sp1, sp2) is observed around 9.6 ppm to 10.6 ppm. It was. Although compound a has two hydroxy groups, only one signal appears because of the overlapping of the two signals derived from the hydroxy group due to the difference in the position of the bromo group. It is done.
また，化合物ａ，ｂでは共に６．８ｐｐｍ〜８．４ｐｐｍ付近にベンゼン環由来のシグナルが観測された。これらを考慮し，ヒドロキシ基由来のシグナル（ｓｐ１）とベンゼン環由来のシグナル（ｂｅｎｚｅｎｅ−ｒｉｎｇ）の積分値を比較した結果，化合物ａではｓｐ１：ｂｅｎｚｅｎｅ−ｒｉｎｇ＝１：７．５（２：１５），化合物ｂはｓｐ１：ｂｅｎｚｅｎｅ−ｒｉｎｇ＝１：１５となり，重複を考慮したそれぞれのプロトン数と一致した。以上のスペクトル解析の結果により，α−ＮＰのイソベンゾフラン縮合環の６位又は５位にブロモ基が導入された２種類の化合物が合成されており，化合物ａが６位に導入された６Ｂｒ−αＮＰ，化合物ｂが５位に導入された５Ｂｒ−αＮＰであることが推定された。 In both compounds a and b, a signal derived from a benzene ring was observed in the vicinity of 6.8 ppm to 8.4 ppm. Considering these, as a result of comparing the integrated value of the signal derived from the hydroxy group (sp1) and the signal derived from the benzene ring (benzone-ring), in the compound a, sp1: benzene-ring = 1: 7.5 (2:15 ), Compound b was sp1: benzen-ring = 1: 15, which coincided with the number of protons in consideration of duplication. As a result of the above spectral analysis, two types of compounds in which a bromo group is introduced at the 6-position or 5-position of the isobenzofuran condensed ring of α-NP have been synthesized, and 6Br— in which compound a is introduced at the 6-position. It was estimated that αNP was 5Br-αNP in which compound b was introduced at the 5-position.
更に，化合物ａ，ｂの色調変化をα−ＮＰと比較したところ，化合物ａ（６Ｂｒ−αＮＰ）はｐＨ９〜１１の塩基性領域において黄色からライトブルーに色調変化を示し，化合物ｂ（５Ｂｒ−αＮＰ）はｐＨ９〜１１の塩基性領域において黄色から青緑色に色調変化を示し，何れの化合物ａ，ｂもｐＨ９〜１１の塩基性領域においてα−ＮＰと類似する明確な色調変化を示すことが確認できた。化合物ａ，ｂが異なる色調変化を示す要因としては，同じくブロモ基が導入されたα―ＮＰであっても，ブロモ基の置換位置が異なるためであると考えられる。とくに化合物ａ（６Ｂｒ−αＮＰ）はα−ＮＰと近似した塩基性領域において近似した色調変化を示していることから，以下の実験では，６Ｂｒ−αＮＰを用いてｐＨ指示用モノマー及びそれを用いたｐＨ指示用共重合体を合成した。ただし，５Ｂｒ−αＮＰの色調変化もα−ＮＰと類似していることから，５Ｂｒ−αＮＰを用いて本発明のｐＨ指示用モノマー及びそれを用いたｐＨ指示用共重合体を合成することも可能である。 Further, when the color tone changes of the compounds a and b were compared with α-NP, the compound a (6Br-αNP) showed a color tone change from yellow to light blue in the basic region of pH 9 to 11, and the compound b (5Br-αNP) ) Shows a change in color tone from yellow to blue-green in the basic region of pH 9-11, and it is confirmed that both compounds a and b show a clear color change similar to α-NP in the basic region of pH 9-11. did it. It is considered that the reason why the compounds a and b show different color tone changes is that the substitution position of the bromo group is different even in α-NP into which the bromo group is introduced. In particular, since compound a (6Br-αNP) shows a color change approximated in a basic region approximated with α-NP, in the following experiment, 6Br-αNP was used and a pH indicating monomer and the same were used. A pH indicating copolymer was synthesized. However, since the color change of 5Br-αNP is similar to that of α-NP, it is possible to synthesize the pH indicating monomer of the present invention and the pH indicating copolymer using the same using 5Br-αNP. It is.
（３）化合物Ｂｒ−αＮＰのブロモ基を重合性基に置換したｐＨ指示用モノマー（６ビニル−αＮＰ）の合成
６Ｂｒ−αＮＰのブロモ基を重合性基（ビニル基）に置換してｐＨ指示用モノマー（５）を合成するため，０．２１９ミリリットル（１．２９ｍｍｏｌ）の４，４，５，５−テトラメチル−２−ビニル−１，３，２−ジオキサボロランと５５９ｍｇ（１．７２ｍｍｏｌ）の炭酸セシウムと３ミリリットルの１，４−ジオキサンとをフラスコに入れて窒素雰囲気下で約２０分撹拌したのち，０．４２７ｇ（０．８６ｍｍｏｌ）の６Ｂｒ−αＮＰと４ミリリットルの１，４−ジオキサンとを加えて更に約２０分撹拌した。
(3) Synthesis of pH-indicating monomer (6 vinyl-αNP) in which the bromo group of compound Br-αNP is substituted with a polymerizable group For pH indication by replacing the bromo group of 6Br-αNP with a polymerizable group (vinyl group) To synthesize monomer (5), 0.219 milliliters (1.29 mmol) of 4,4,5,5-tetramethyl-2-vinyl-1,3,2-dioxaborolane and 559 mg (1.72 mmol) of carbonic acid Cesium and 3 milliliters of 1,4-dioxane were placed in a flask and stirred under a nitrogen atmosphere for about 20 minutes, and then 0.427 g (0.86 mmol) of 6Br-αNP and 4 milliliters of 1,4-dioxane were added. In addition, the mixture was further stirred for about 20 minutes.
次いで，２４．５ｍｇの，テトラキス（トリフェニルホスフィン）パラジウム（０）と１ミリリットルの１，４−ジオキサンとを加えて更に約２０分撹拌し，最後にフラスコ内の温度を１００℃にして撹拌しながら２４時間反応させた。反応後，化合物を常温に戻して濾過により炭酸セシウムを取り除き，濾液を減圧乾燥させて化合物を得た。得られた化合物をヘキサン：アセトン（６：４）の展開溶媒を用いてカラムクロマトグラフィーにより精製し，Ｒｆ値＝０．３７の橙色の単体化合物を得た。 Next, 24.5 mg of tetrakis (triphenylphosphine) palladium (0) and 1 ml of 1,4-dioxane were added, and the mixture was further stirred for about 20 minutes. Finally, the temperature in the flask was brought to 100 ° C. and stirred. The reaction was continued for 24 hours. After the reaction, the compound was returned to room temperature, cesium carbonate was removed by filtration, and the filtrate was dried under reduced pressure to obtain a compound. The obtained compound was purified by column chromatography using a developing solvent of hexane: acetone (6: 4) to obtain an orange simple compound having an Rf value = 0.37.
（４）合成したｐＨ指示用モノマー（６ビニル−αＮＰ）の構造の推定
精製により得られた単体化合物の構造を推定するため，化合物を重ＤＭＳＯに溶解させて核磁気共鳴スペクトル（１Ｈ−ＮＭＲ）を求めた。得られた化合物のスペクトルを図２（Ｂ）に示す。図２（Ａ）には，合成前の６Ｂｒ−αＮＰのスペクトルを併せて示している。図２から分かるように，新たな化合物のスペクトルには５．０ｐｐｍ〜７．０ｐｐｍ付近に新たなシグナル（ｓｐ３〜ｓｐ５）が出現していることが観測された。これは，重合性基であるビニル基由来のシグナルであると考えられる。また，６．８ｐｐｍ〜８．２ｐｐｍ付近には合成前の６Ｂｒ−αＮＰと類似したシグナルが観察された。以上のスペクトル解析の結果から，ｐＨ指示用モノマーとして，ブロモ基を重合性基であるビニル基に置換した６ビニル−αＮＰが合成されていることが推定された。
(4) Estimation of the structure of the synthesized pH indicator monomer (6 vinyl-αNP) In order to estimate the structure of the simple compound obtained by purification, the compound was dissolved in deuterated DMSO and nuclear magnetic resonance spectrum (1H-NMR) Asked. The spectrum of the obtained compound is shown in FIG. FIG. 2A also shows the spectrum of 6Br-αNP before synthesis. As can be seen from FIG. 2, it was observed that a new signal (sp3 to sp5) appeared in the vicinity of 5.0 ppm to 7.0 ppm in the spectrum of the new compound. This is considered to be a signal derived from a vinyl group which is a polymerizable group. In addition, a signal similar to 6Br-αNP before synthesis was observed in the vicinity of 6.8 ppm to 8.2 ppm. From the results of the above spectral analysis, it was estimated that 6-vinyl-αNP in which the bromo group was substituted with a vinyl group which is a polymerizable group was synthesized as a pH indicating monomer.
なお，ｐＨ指示用モノマーの重合性基はビニル基に限定されるわけではなく，（メタ）アクリルロイル基，（メタ）アクリルロイルオキシ基，ビニル基のように不飽和結合で付加重合できる基，又は，アミノ基，カルボキシル基，アルデヒド基，環状エーテル基のように縮合重合できる基等を重合性基とすることもできる。また，式（５）のようにｐＨ指示部位であるαＮＰと重合性基とを直接結合させることに代えて，アルキレン基，エーテル結合，カルボニル基，アミド結合（−ＣＯ−ＮＨ−）の少なくとも一種を介して結合させることもできる。これらの基のうちでは，アルキレン基又はエーテル結合がとくに好ましい。 In addition, the polymerizable group of the pH indicating monomer is not limited to a vinyl group, but a group capable of addition polymerization with an unsaturated bond such as a (meth) acryloyl group, a (meth) acryloyloxy group, a vinyl group, Alternatively, a polymerizable group such as an amino group, a carboxyl group, an aldehyde group, or a cyclic ether group can be used as the polymerizable group. Further, instead of directly bonding αNP, which is a pH indicator site, and a polymerizable group as in Formula (5), at least one of an alkylene group, an ether bond, a carbonyl group, and an amide bond (—CO—NH—) It is also possible to combine them via Of these groups, an alkylene group or an ether bond is particularly preferable.
（５）ｐＨ指示用モノマー（６ビニル−αＮＰ）を用いたｐＨ指示用共重合体の作製
合成した新規なｐＨ指示用モノマーである６ビニル−αＮＰを，非イオン性モノマーであるＮ−イソプロピルアクリルアミド（ＮＩＰＡＡｍ）と共重合させて（６）式の共重合体が作製できることを確認するため，４０５．４ｍｇ（３．９８ｍｍｏｌ）のＮＩＰＡＡｍと８．８９ｍｇ（０．０２ｍｍｏｌ）の６ビニル−αＮＰとを二口フラスコに入れ，溶媒として２ミリリットルのＤＭＦ（ジメチルホルムアミド）を加え，純窒素ガスをフローしながら約３０分間撹拌した。
(5) Preparation of pH-indicating copolymer using pH-indicating monomer (6 vinyl-αNP) The synthesized novel pH-indicating monomer, 6 vinyl-αNP, is a non-ionic monomer, N-isopropylacrylamide. In order to confirm that a copolymer of the formula (6) can be prepared by copolymerization with (NIPAAm), 405.4 mg (3.98 mmol) of NIPAAm and 8.89 mg (0.02 mmol) of 6 vinyl-αNP are used. The solution was placed in a two-necked flask, 2 ml of DMF (dimethylformamide) was added as a solvent, and the mixture was stirred for about 30 minutes while flowing pure nitrogen gas.
次いで，重合開始剤として１０．９ｍｇ（０．０６７ｍｍｏｌ）のＡＩＢＮ（アゾビスイソブチロニトリル）を加えて約３０分間撹拌したのち，温度６０℃に設定したオイルバス中で加熱・撹拌しながら約２４時間反応させた。反応終了後，パスツールピペットを用いて反応物を，ビーカーに入れた３０００ミリリットルのジエチルエーテルに少しずつ滴下して再沈殿させた。最後に，沈殿物を濾過して真空ポンプで減圧乾燥することにより，共重合体を得た。 Next, 10.9 mg (0.067 mmol) of AIBN (azobisisobutyronitrile) is added as a polymerization initiator and stirred for about 30 minutes, and then heated and stirred in an oil bath set at a temperature of 60 ° C. for about 30 minutes. The reaction was performed for 24 hours. After completion of the reaction, the reaction product was added dropwise to 3000 ml of diethyl ether in a beaker using a Pasteur pipette and reprecipitated. Finally, the precipitate was filtered and dried under reduced pressure with a vacuum pump to obtain a copolymer.
得られた共重合体の構造を推定するため，共重合体を重ＤＭＳＯに溶解させて核磁気共鳴スペクトル（１Ｈ−ＮＭＲ）を求めた。得られた化合物のスペクトルを図３（Ｂ）に示す。図３（Ａ）には，共重合させる前の６ビニル−αＮＰのスペクトルを併せて示している。図３（Ｂ）のスペクトルには，４．０ｐｐｍ付近にＮＩＰＡＡｍの−ＣＨ（ＣＨ３）２基由来のシグナル（ｓｐ６）が出現していることが観測された。また，図３（Ａ）のスペクトルとの比較から分かるように，１０．４ｐｐｍ付近に６ビニル−αＮＰと同様の−ＯＨ基由来のシグナル（ｓｐ７）が出現していることが観測された。このスペクトル解析の結果から，６ビニル−αＮＰとＮＩＰＡＡｍとが，０．５：９９．５（ｍｏｌ％）で共重合していることが推定された。なお，実験では溶媒としてＤＭＦを用いたが，より極性の高いＤＭＳＯ（ジメチルスルホキシド）等を用いることも有効である。 In order to estimate the structure of the obtained copolymer, the copolymer was dissolved in deuterated DMSO to obtain a nuclear magnetic resonance spectrum (1H-NMR). The spectrum of the obtained compound is shown in FIG. FIG. 3A also shows the spectrum of 6 vinyl-αNP before copolymerization. In the spectrum of FIG. 3B, it was observed that a signal (sp6) derived from NIPAAm —CH (CH 3 ) 2 group appeared in the vicinity of 4.0 ppm. Further, as can be seen from comparison with the spectrum of FIG. 3A, it was observed that a signal (sp7) derived from —OH group similar to 6vinyl-αNP appeared in the vicinity of 10.4 ppm. From the result of this spectrum analysis, it was estimated that 6 vinyl-αNP and NIPAAm were copolymerized at 0.5: 99.5 (mol%). In the experiment, DMF was used as a solvent, but it is also effective to use DMSO (dimethyl sulfoxide) or the like having higher polarity.
新規な６ビニル−αＮＰを用いた共重合体が作製できることを確認したのち，更に三次元網目構造の色調変化型ｐＨ指示用共重合体とするため，架橋剤であるＭＢＡＡｍ（Ｎ，Ｎ−メチレンビスアクリルアミド）を含めた表１の重合条件で，６ビニル−αＮＰとＮＩＰＡＡｍとを共重合させて共重合体（７）を作製した。溶媒としてＴＨＦ（テトラハイドロフラン）と水との混合溶媒を用い，重合開示剤としてＡＰＳ（過硫酸アンモニウム），及びＴＭＥＤ（Ｎ，Ｎ，Ｎ’，Ｎ’−テトラメチルエチレンジアミン）を用いた。反応終了後の沈殿物を濾過して真空ポンプで減圧乾燥することにより，水に不溶で水を吸収してゲル状になるｐＨ指示用共重合体が得られた。
After confirming that a copolymer using a novel 6 vinyl-αNP can be prepared, in order to make a color change type pH indicating copolymer having a three-dimensional network structure, MBAAm (N, N-methylene) as a cross-linking agent is used. Under the polymerization conditions in Table 1 including bisacrylamide), 6 vinyl-αNP and NIPAAm were copolymerized to prepare a copolymer (7). A mixed solvent of THF (tetrahydrofuran) and water was used as the solvent, and APS (ammonium persulfate) and TMED (N, N, N ′, N′-tetramethylethylenediamine) were used as the polymerization disclosure agent. The precipitate after completion of the reaction was filtered and dried under reduced pressure with a vacuum pump to obtain a pH indicating copolymer that was insoluble in water and absorbed into water to form a gel.
作製したｐＨ指示用共重合体を用いて複数の試験片（１×１ｃｍ）を成形し，各試験片をｐＨ１間隔で調製した異なるｐＨ値０〜１２の水溶液にそれぞれ浸漬して発色させ，上述した特許文献３の場合と同様に，各試験片の発色を白色点Ｏが中央に配置された図７（Ａ）の色度図Ｍ１上にプロットしてその白色点Ｏが中心の極座標上の発色点Ｃの偏角Ｄを検出し，各試験片の発色点Ｃの偏角ＤとｐＨ値との関係をロジスティックモデル（ロジスティック曲線）で近似した関係式Ｆ２を求めた。求めた関係式Ｆ２を図４に示す。 A plurality of test pieces (1 × 1 cm) are formed using the prepared pH indicating copolymer, and each test piece is dipped in an aqueous solution having different pH values of 0 to 12 prepared at pH 1 intervals to develop the color. As in the case of Patent Document 3, the color development of each test piece is plotted on the chromaticity diagram M1 in FIG. 7A in which the white point O is arranged at the center, and the white point O is on the polar coordinates at the center. The deviation angle D of the color development point C was detected, and a relational expression F2 in which the relationship between the deviation angle D of the color development point C of each test piece and the pH value was approximated by a logistic model (logistic curve) was obtained. The obtained relational expression F2 is shown in FIG.
図４の関係式Ｆ２は，６ビニル−αＮＰを用いた色調変化型ｐＨ指示用共重合体が，ｐＨ６〜１２の塩基性領域において黄色から青色（ライトブルー）に色調変化しており，ｐＨが増加すると偏角Ｄも増加しながら上に凹の状態から凸の状態に変わる曲線となっており，変曲点におけるｐＨ（＝ｐＫａ）が約９．９であることを示している。また本発明者は，６ビニル−αＮＰとＮＩＰＡＡｍと共に，イオン性部位及び重合性部位を有するイオン性モノマーを含めて共重合させることによりに，関係式Ｆ２の色調変化するｐＨ領域を塩基性側又は酸性側へシフトさせることができることも確認した。従って，図４のようなｐＨ指示用共重合体を用いることにより，ｐＨ６〜１２を含めて広い塩基性領域におけるｐＨモニタリングを実現することができる。 The relational expression F2 in FIG. 4 shows that the color-changing pH indicating copolymer using 6 vinyl-αNP changes in color from yellow to blue (light blue) in the basic region of pH 6-12. As the declination D increases, the curve changes from a concave state to a convex state while increasing, indicating that the pH (= pKa) at the inflection point is about 9.9. In addition, the present inventor co-polymerizes 6 vinyl-αNP and NIPAAm together with an ionic monomer having an ionic site and a polymerizable site to thereby change the pH range where the color tone of the relational formula F2 changes to the basic side or It was also confirmed that it can be shifted to the acidic side. Therefore, by using the pH indicating copolymer as shown in FIG. 4, pH monitoring in a wide basic region including pH 6 to 12 can be realized.
また，表２の重合条件でジメチルアミノアゾベンゼンアクリレート（ＡＡＢＡＡ）とＮＩＰＡＡｍとを共重合させたｐＨ指示用共重合体を作製し，その共重合体を異なるｐＨ値０〜１２の水溶液に浸漬したときの発色を図７（Ａ）の色度図Ｍ１上にプロットして求めた偏角ＤとｐＨ値との関係式Ｆ１を図５に示す。図５には，関係式Ｆ１と共に，上述した６ビニル−αＮＰを用いた色調変化型ｐＨ指示用共重合体の関係式Ｆ２を併せて示している。 Further, when a pH indicating copolymer obtained by copolymerizing dimethylaminoazobenzene acrylate (AABAA) and NIPAAm under the polymerization conditions shown in Table 2 was prepared, and the copolymer was immersed in aqueous solutions having different pH values of 0 to 12 FIG. 5 shows a relational expression F1 between the declination angle D and the pH value obtained by plotting the above color development on the chromaticity diagram M1 of FIG. In FIG. 5, together with the relational expression F1, the relational expression F2 of the above-described color tone changing copolymer using 6 vinyl-αNP is also shown.
図５の関係式Ｆ１は，ＡＡＢＡＡを用いた色調変化型ｐＨ指示用共重合体が，ｐＨ２〜７の酸性領域において赤色から黄色に色調変化しており，ｐＨが増加すると偏角Ｄも増加しながら上に凹の状態から凸の状態に変わる曲線となっており，変曲点におけるｐＨ（＝ｐＫａ）が約３.３であることを示している。また，図５の関係式Ｆ１及びＦ２は，ＡＡＢＡＡを用いたｐＨ指示用共重合体と，６ビニル−αＮＰを用いたｐＨ指示用共重合体とを組み合わせることにより，酸性から塩基性にわたるｐＨ２〜１２程度の広範囲におけるｐＨモニタリングが実現できることを示している。例えば，ＡＡＢＡＡを用いた共重合体と６ビニル−αＮＰを用いた共重合体とからなる一対の共重合体として用い，測定対象の液体に一対の共重合体を同時に浸漬させて発色させ，両者の発色から求めた偏角Ｄが共にゼロのときはｐＨ２以下の酸性であり，ビニル−αＮＰの発色から求めた偏角ＤはゼロであるがＡＡＢＡＡの発色から偏角Ｄが求めるときはｐＨ２〜７の酸性ないし中性であり，更にビニル−αＮＰの発色から偏角Ｄが求めるときはｐＨ７〜１２の塩基性であると判断することができる。 The relational expression F1 in FIG. 5 shows that the color-changing pH indicating copolymer using AABAA changes from red to yellow in the acidic region of pH 2 to 7, and the declination angle D increases as the pH increases. However, the curve changes from a concave state to a convex state, indicating that the pH (= pKa) at the inflection point is about 3.3. In addition, the relational expressions F1 and F2 in FIG. 5 are obtained by combining pH-indicating copolymer using AABAA and pH-indicating copolymer using 6vinyl-αNP, to have a pH value ranging from acidic to basic. It shows that pH monitoring in a wide range of about 12 can be realized. For example, it is used as a pair of copolymers consisting of a copolymer using AABAA and a copolymer using 6 vinyl-αNP, and a pair of copolymers are simultaneously immersed in a liquid to be measured to develop a color. When the declination D determined from the color development of both is zero, the pH is 2 or less, and the declination D determined from the color development of vinyl-αNP is zero, but when the declination D is determined from the color development of AABAA, the pH 2 7 is acidic to neutral, and when the deviation angle D is determined from the color of vinyl-αNP, it can be determined that the pH is 7 to 12.
こうして本発明の目的である「塩基性範囲で色調変化するｐＨ指示用モノマー及びそれを用いた色調変化型共重合体」の提供を達成することができる。 Thus, it is possible to achieve the object of the present invention, “a pH indicating monomer that changes color tone in the basic range, and a color tone changing copolymer using the same”.
図５の関係式Ｆ１，Ｆ２は，共にｐＨが増加すると偏角Ｄも増加しながら上に凹の状態から凸の状態に変わる曲線となっており，６ビニル−αＮＰを用いたｐＨ指示用共重合体のｐＫａが約９．９であるのに対し，ＡＡＢＡＡを用いたｐＨ指示用共重合体のｐＫａが約３.３であることを示しているので，両者を含めて同一高分子鎖に共重合すれば，変曲点を２つ持つような色調変化型ｐＨ指示用共重合体が合成できることを示唆している。そこで，異なるｐＨ領域で色調変化する６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーとＡＡＢＡＡを用いた第２ｐＨ指示用モノマーとを，表３の条件で非イオン性モノマーであるＮＩＰＡＡｍと共重合させてｐＨ指示用共重合体（８）を作製した。
The relational expressions F1 and F2 in FIG. 5 are curves that change from a concave state to a convex state while the declination angle D increases as the pH increases. Both of the pH indications using 6 vinyl-αNP. Since the pKa of the polymer is about 9.9, the pKa of the pH indicating copolymer using AABAA is about 3.3. This suggests that by copolymerization, a color-change-type pH indicating copolymer having two inflection points can be synthesized. Therefore, a first pH indicating monomer using 6 vinyl-αNP and a second pH indicating monomer using AABAA, which change color tone in different pH ranges, are copolymerized with NIPAAm, which is a nonionic monomer, under the conditions shown in Table 3. Thus, a pH indicating copolymer (8) was produced.
作製したｐＨ指示用共重合体を用いて複数の試験片（２×２ｃｍ）を成形し，各試験片をｐＨ１間隔で調製した異なるｐＨ値０〜１２の水溶液にそれぞれ浸漬して発色させ，上述した特許文献３の場合と同様に，各試験片の発色を白色点Ｏが中央に配置された図７（Ａ）の色度図Ｍ１上にプロットしてその白色点Ｏが中心の極座標上の発色点Ｃの偏角Ｄを検出し，各試験片の発色点Ｃの偏角ＤとｐＨ値との関係をロジスティックモデル（ロジスティック曲線）で近似した関係式Ｆ３を求めた。求めた関係式Ｆ３を図６に示す。 A plurality of test pieces (2 × 2 cm) are formed using the prepared pH indicating copolymer, and each test piece is dipped in an aqueous solution having a different pH value of 0 to 12 prepared at pH 1 intervals to cause color development. As in the case of Patent Document 3, the color development of each test piece is plotted on the chromaticity diagram M1 in FIG. 7A in which the white point O is arranged at the center, and the white point O is on the polar coordinates at the center. The deviation angle D of the coloring point C was detected, and a relational expression F3 that approximated the relationship between the deviation angle D of the coloring point C and the pH value of each test piece with a logistic model (logistic curve) was obtained. The obtained relational expression F3 is shown in FIG.
図６の関係式Ｆ３は，６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーとＡＡＢＡＡを用いた第２ｐＨ指示用モノマーとを共重合させたｐＨ指示用共重合体が，ｐＨ２〜７の酸性領域において赤色から黄色に色調変化しており，ｐＨ２〜３において第１の変曲点が存在することを示している。また，ｐＨ７〜１２の塩基性領域において黄色から青色に色調変化しており，ｐＨ９〜１１において第２の変曲点が存在することを示している。すなわち，６ビニル−αＮＰを用いたｐＨ指示用モノマーとＡＡＢＡＡを用いたｐＨ指示用モノマーとを共重合させることにより，ｐＨ２〜３とｐＨ９〜１１と２つの変色点を有し，赤色から黄色を経て青色に色調変化する２段階の変色を示すｐＨ指示用共重合体とすることができ，単独の共重合体で酸性から塩基性にわたる広範囲におけるｐＨモニタリングが実現できることを確認することができた。 The relational expression F3 in FIG. 6 shows that the pH indicating copolymer obtained by copolymerizing the first pH indicating monomer using 6 vinyl-αNP and the second pH indicating monomer using AABAA has an acidic region of pH 2 to 7. The color tone changes from red to yellow at pH 2, and the first inflection point is present at pH 2 to 3. In addition, the color tone changes from yellow to blue in the basic region of pH 7 to 12, indicating that the second inflection point exists at pH 9 to 11. That is, by copolymerizing a pH indicator monomer using 6 vinyl-αNP and a pH indicator monomer using AABAA, it has two discoloration points, pH 2-3 and pH 9-11, and changes from red to yellow. As a result, it was possible to obtain a pH-indicating copolymer exhibiting two-stage color change that changes the color tone to blue, and it was confirmed that pH monitoring in a wide range from acidic to basic could be realized with a single copolymer.
なお，本発明による６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーを，ＡＡＢＡＡを用いたｐＨ指示用モノマーに代えて，その第１ｐＨ指示用モノマーと異なるｐＨ領域で色調変化する他のｐＨ指示用モノマー（第２ｐＨ指示用モノマー）と共重合することも有効である。例えば，酸性ｐＨ領域において色調変化を示すような従来の低分子のｐＨ指示薬（例えばメチルレッド等）に重合性基を導入し，酸性ｐＨ領域において類似の色調変化を示すような第２ｐＨ指示用モノマーを作り出すことができれば，そのような第２ｐＨ指示用モノマーと６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーとを共重合させることにより，図６の場合と同様に２段階で色調変化を示すようなｐＨ指示用共重合体を作製することが期待できる。 The first pH indicating monomer using 6 vinyl-αNP according to the present invention is replaced with the pH indicating monomer using AABAA, and other pH indicating monomers that change color tone in a different pH range from the first pH indicating monomer. It is also effective to copolymerize with a monomer (second pH indicating monomer). For example, a second pH indicating monomer that exhibits a similar color change in an acidic pH region by introducing a polymerizable group into a conventional low molecular pH indicator (such as methyl red) that exhibits a color change in the acidic pH range. Can be produced by copolymerizing such a second pH indicating monomer and a first pH indicating monomer using 6 vinyl-αNP, as shown in FIG. It can be expected to produce a pH-indicating copolymer.
６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーと，異なるｐＨ領域で色調変化する第２ｐＨ指示用モノマーとを共重合させて２段階の変色を示すようなｐＨ指示用共重合体を作製する場合は，第１ｐＨ指示用モノマーを変色させる第１ｐＨ範囲と第２ｐＨ指示用モノマーを変色させる第２ｐＨ範囲との中間域（重なり域である場合を含む）において両ｐＨ指示用モノマーが相互に近似色であるか又は少なくとも一方が無色であり，第１ｐＨ範囲及び第２ｐＨ範囲の両端域において両ｐＨ指示用モノマーが異なる色であることが望ましい。すなわち，図７を参照して上述したように，共重合体の発色から色度図Ｍ１上の偏角Ｄを介してｐＨ値を求める方法を用いる場合は，両ｐＨ指示用モノマーが第１ｐＨ範囲及び第２ｐＨ範囲の中間域（すなわち中性領域）において近似色であり，両端域（酸性側端と塩基性側端）において異なる色であれば，それらを共重合させたｐＨ指示用共重合体の発色点を色度図Ｍ１上に白色点Ｏを中心として弧を描くように並べることができ，図６の場合と同様に２段階で色調変化させることができる。また，ｐＨが増加すると色度図Ｍ１上の偏角Ｄも増加するように，第１ｐＨ指示用モノマーと第２ｐＨ指示用モノマーとの混合比率を適当に調整することができる。 When copolymerizing a first pH indicating monomer using 6-vinyl-αNP and a second pH indicating monomer that changes color tone in a different pH range to produce a pH indicating copolymer that exhibits two-stage discoloration Is an approximate color of both pH indicating monomers in an intermediate range (including the overlapping range) between the first pH range for changing the color of the first pH indicating monomer and the second pH range for changing the color of the second pH indicating monomer. It is desirable that at least one of them is colorless and both pH indicating monomers are different colors in both end ranges of the first pH range and the second pH range. That is, as described above with reference to FIG. 7, when using the method of obtaining the pH value from the color development of the copolymer via the declination D on the chromaticity diagram M1, both pH indicating monomers are in the first pH range. And a pH indicating copolymer obtained by copolymerizing these colors if they are approximate colors in the intermediate range (that is, neutral range) of the second pH range and different colors in both end ranges (acid side end and basic side end). The color development points can be arranged on the chromaticity diagram M1 so as to draw an arc with the white point O as the center, and the color tone can be changed in two stages as in the case of FIG. Further, the mixing ratio of the first pH indicating monomer and the second pH indicating monomer can be appropriately adjusted so that the deviation angle D on the chromaticity diagram M1 increases as the pH increases.
６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーは，上述したように，ｐＨ６〜１２の塩基性領域（第１ｐＨ範囲）において黄色から青色（ライトブルー）へと色調変化を示す。これに対して酸性領域（第２ｐＨ範囲）において色調変化を示す第２ｐＨ指示用モノマーと共重合させてｐＨ指示用共重合体とした場合は，第１ｐＨ範囲と第２ｐＨ範囲との中間域，すなわち中性領域において第２ｐＨ指示用モノマーが黄色と近似色であり，第２ｐＨ範囲の低ｐＨ端（すなわち酸性側端）において第１ｐＨ範囲の高ｐＨ端（すなわち塩基性側端）の青色と異なる色（例えば赤色）であれば，ｐＨ指示用共重合体のｐＨ値に応じた発色を色度図Ｍ１上に白色点Ｏを中心として弧を描くように並べることができ，図６の場合と同様に２段階で色調変化を示すようなｐＨ指示用共重合体を作製することができる。 As described above, the first pH indicator monomer using 6 vinyl-αNP exhibits a color tone change from yellow to blue (light blue) in the basic region (first pH range) of pH 6-12. On the other hand, when copolymerized with a second pH indicating monomer exhibiting a color tone change in the acidic region (second pH range) to obtain a pH indicating copolymer, an intermediate region between the first pH range and the second pH range, In the neutral region, the second pH indicating monomer is an approximate color of yellow, and is different from the blue color at the high pH end (ie basic side end) of the first pH range at the low pH end (ie acid side end) of the second pH range. If it is (for example, red), the color development according to the pH value of the pH indicating copolymer can be arranged on the chromaticity diagram M1 so as to draw an arc around the white point O as in the case of FIG. It is possible to produce a pH indicating copolymer that exhibits a change in color tone in two stages.
また，酸性領域において色調変化を示す第２ｐＨ指示用モノマーとして，第１ｐＨ範囲と第２ｐＨ範囲との中間域，すなわち中性領域において無色であり，第２ｐＨ範囲の低ｐＨ端において青色と異なる色であるものを用いることも有効である。６ビニル−αＮＰを用いた第１ｐＨ指示用モノマーとそのような第２ｐＨ指示用モノマーとを共重合させたｐＨ指示用共重合体を作製すれば，ｐＨ値に応じた発色を色度図Ｍ１上に白色点Ｏを中心として弧を描くように並べることができ，図６の場合と同様に２段階で色調変化を示すようなｐＨ指示用共重合体とすることが可能である。 Further, as a second pH indicating monomer exhibiting a color change in the acidic region, it is colorless in the intermediate region between the first pH range and the second pH range, that is, in the neutral region, and different from blue at the low pH end of the second pH range. It is also effective to use something. By producing a pH indicating copolymer obtained by copolymerizing a first pH indicating monomer using 6 vinyl-αNP and such a second pH indicating monomer, color development corresponding to the pH value is shown on the chromaticity diagram M1. Can be arranged so as to draw an arc with the white point O as the center, and it is possible to obtain a pH indicating copolymer that shows a change in color tone in two stages, as in the case of FIG.
Ｃ…発色点 Ｄ…偏角
Ｆ…関係式 Ｍ…色度図
Ｏ…白色点
C ... Color development point D ... Deflection angle F ... Relational expression M ... Chromaticity diagram O ... White point
本発明による塩基性色調変化型ｐＨ指示用モノマーは，式（１）で表されるαナフトールフタレインのイソベンゾフラン縮合環の６位又は５位に重合性基を結合してなり，塩基性ｐＨ領域で色調変化するものである。
The basic color-changing type pH indicating monomer according to the present invention is formed by bonding a polymerizable group to the 6- or 5-position of the isobenzofuran condensed ring of α-naphtholphthalein represented by the formula (1). The color changes in the area.
（１）α−ＮＰにブロモ基（Ｂｒ）を導入した化合物Ｂｒ−αＮＰの合成
まず，α−ＮＰのイソベンゾフラン縮合環の６位又は５位にブロモ基（Ｂｒ）を導入した化合物（４）を得るため，１．５ｇ（６．０ｍｍｏｌ）の６−ブロモフタル酸無水物と２．０ｇ（１２ｍｍｏｌ）の１−ナフトールとを試験管に入れ，触媒として１０６μリットルの濃硫酸（９５％）を滴下したのち蓋をしてビーカーに入れ，適宜撹拌しながら１７０Ｗの電子レンジで試薬がすべて溶けるまで加熱し，全体が緑色の反応物を得た。
(1) Synthesis of compound Br-αNP in which bromo group (Br) is introduced into α-NP First, compound (4) in which bromo group (Br) is introduced into the 6- or 5-position of the isobenzofuran condensed ring of α-NP. To obtain 1.5 g (6.0 mmol) of 6-bromophthalic anhydride and 2.0 g (12 mmol) of 1-naphthol, and 106 μl of concentrated sulfuric acid (95%) was added dropwise as a catalyst. After that, the lid was put in a beaker and heated with a 170 W microwave oven with proper stirring until all the reagents were dissolved to obtain a green reaction product as a whole.
Claims (8)
A basic color-changing type pH indicating monomer which has a polymerizable group bonded to the 6- or 5-position of the isobenzofuran condensed ring of α-naphtholphthalein represented by the formula (1) and changes color in the basic pH range .
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US11471335B2 (en) | 2018-09-05 | 2022-10-18 | University Of South Carolina | Gel-within-gel wound dressing |
| US11698344B2 (en) | 2018-09-05 | 2023-07-11 | University Of South Carolina | PH indicator swabs for biomonitoring and diagnostics |
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| US20090185956A1 (en) * | 2008-01-18 | 2009-07-23 | Michael Carl Junger | pH SENSITIVE INDICATOR DEVICE |
| JP2012163484A (en) * | 2011-02-08 | 2012-08-30 | Tokyo Denki Univ | COPOLYMER FOR pH INDICATION, AND pH MONITORING DEVICE AND pH MEASUREMENT METHOD USING THE SAME |
| JP2015018221A (en) * | 2013-06-11 | 2015-01-29 | 信越化学工業株式会社 | Underlayer film material and pattern forming method |
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|---|---|---|---|---|
| JPH05215743A (en) * | 1992-02-03 | 1993-08-24 | Neos Co Ltd | Method for forming coating layer including ph indicator |
| JPH06192213A (en) * | 1992-10-14 | 1994-07-12 | C R Bard Inc | Amino substituted phenol red as ph indicator and preparation |
| US20090185956A1 (en) * | 2008-01-18 | 2009-07-23 | Michael Carl Junger | pH SENSITIVE INDICATOR DEVICE |
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| JP2015018221A (en) * | 2013-06-11 | 2015-01-29 | 信越化学工業株式会社 | Underlayer film material and pattern forming method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US11471335B2 (en) | 2018-09-05 | 2022-10-18 | University Of South Carolina | Gel-within-gel wound dressing |
| US11698344B2 (en) | 2018-09-05 | 2023-07-11 | University Of South Carolina | PH indicator swabs for biomonitoring and diagnostics |
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