本發明因此係關於下式I化合物，I 其中 X 表示F或CF3
， m 表示1或2、較佳1， R1
表示具有1至15個C原子之鹵化或未經取代之烷基，其中另外，該等基團中之一或多個CH2
基團可以O原子彼此不直接連接之方式各自彼此獨立地由-C≡C-、-CH=CH-、-(CO)O-、-O(CO)-、-(CO)-或-O-替代；或可聚合基團， A 表示 a) 1,4-伸苯基，其中一或兩個CH基團可由N替代，且其中另外，一或多個H原子可由Br、Cl、F、CN、甲基、甲氧基或單氟化或多氟化甲基或甲氧基替代， b) 反式-1,4-伸環己基或伸環己烯基，其中另外，一或多個非毗鄰CH2
基團可由-O-及/或-S-替代且其中H可由F取代， Z1
表示單鍵、-CH2
O-、-(CO)O-、-CF2
O-、-CH2
CH2
CF2
O-、-CF2
CF2
-、-CH2
CF2
-、-CH2
CH2
-、-(CH2
)4
-、-CH=CH-、-CH=CF-、-CF=CF-或-C≡C-，其中不對稱橋可經定向至兩側， L1
、L2
彼此獨立地表示H或F，較佳H，且 n 表示1、2或3。 本發明此外係關於式I化合物在液晶介質中之用途。 本發明同樣係關於具有至少兩種液晶組分之液晶介質，該等液晶組分包含至少一種式I化合物。 式I化合物具有寬應用範圍。端視取代基之選擇而定，該等化合物可用作主要構成液晶介質之基礎材料；然而，亦可將來自其他類別化合物之液晶基礎材料添加至式I化合物，以(例如)影響此類型電介質之介電及/或光學各向異性及/或最佳化其臨限電壓及/或其黏度。 在純態下，式I化合物係無色的且其自身或在混合物中在有利於電光用途所處之溫度範圍中形成液晶中間相。本發明化合物使能夠達成寬向列相範圍。在液晶混合物中，與具有高介電各向異性之相當化合物相比，本發明之物質顯著增加光學各向異性及/或導致低溫儲存穩定性之改良。同時，與自先前技術已知之在環之間含有橋接要素(例如，-C≡C-或-CF=CF-)之材料相比，化合物以經改良UV穩定性為特徵。 Z1
在各情形下獨立地較佳表示單鍵、-CF2
O-、-OCF2
-、-C2
F4
-、-CH2
O-、-OCH2
-、-C≡C-或-(CO)O-，尤其單鍵。 A1
較佳表示且此外或。 R1
較佳表示具有最多8個碳原子之烷基、烷氧基、烯基或烯氧基或可聚合基團。R1
尤佳表示具有1、2、3、4、5、6或7個C原子之無支鏈烷基或烯基。R1
極佳表示乙基或正丙基。 含有具支鏈或經取代之翼狀基團R1
之式I化合物偶爾可能因在習用液晶基礎材料中較佳之溶解性而甚為重要。基團R1
較佳係直鏈。 取代基X較佳表示CF3
。 較佳者係式I化合物，其中L1
及L2
表示氫原子。 較佳者係式I化合物，其中n係2。 尤佳之式I化合物係下式化合物：I1I2I3I4I5I6I7I8I9I10I11I12I13I14 其中X、m及R1
獨立地具有上文所指示之含義，尤其其較佳含義或組合。在式I1至I14之化合物中，式I1、I2、I3、I8、I9、I10及I11較佳，尤其式I1及I10以及I11之化合物。 尤佳者亦係下式之說明性化合物： 其中R1
係如上文所定義，較佳表示具有1、2、3、4、5、6或7個C原子之無支鏈烷基或烯基。 式I化合物係藉由本身已知之方法製備，如文獻(例如在權威著作中，例如Houben-Weyl，Methoden der organischen Chemie [Methods of Organic Chemistry]，Georg-Thieme-Verlag，Stuttgart)中所述，確切而言係在適於該等反應之已知反應條件下進行。此處亦可使用本身已知之變化形式，但此處不再更詳細提及。 式I化合物可明顯的自以下說明性合成及實例(方案1及2)有利地製備： 方案 1.
用於製備式I化合物(其中X = F)之一般合成方案。 方案 2.
用於製備式I化合物(其中X = CF3
)之一般合成方案。 對應起始材料通常可由熟習此項技術者容易地藉由自文獻已知之合成方法製備。反應細節係由工作實例所揭示。 本發明亦關於包含一或多種本發明式I化合物之液晶介質。液晶介質包含至少兩種組分。其較佳係藉由將組分彼此混合而獲得。因此用於製備液晶介質之本發明製程之特徵在於，將至少一種式I化合物與至少一種另一液晶原化合物混合，且視情況添加添加劑。 澄清點、低溫下之黏度、熱及UV穩定性及介電各向異性可達成之組合與來自先前技術之先前材料極好地互補。 本發明之液晶介質較佳包含2至40、尤佳4至30種組分作為除一或多種本發明化合物以外之其他成分。特定而言，該等介質包含除一或多種本發明化合物以外之7至25種組分。該等其他成分較佳係選自向列型或向列態(nematogenic) (單變性或各向同性)物質、特定而言係來自以下類別之物質：氧偶氮苯、亞苄基苯胺、聯苯、聯三苯、苯甲酸苯基酯或苯甲酸環己酯、環己烷甲酸之苯基酯或環己基酯、環己基苯甲酸之苯基酯或環己基酯、環己基環己烷甲酸之苯基酯或環己基酯、苯甲酸、環己烷甲酸或環己基環己烷甲酸之環己基苯基酯、苯基環己烷、環己基聯苯、苯基環己基環己烷、環己基環己烷、環己基環己基環己烷、1,4-雙環己基苯、4,4'-雙環己基聯苯、苯基嘧啶或環己基嘧啶、苯基吡啶或環己基吡啶、苯基二噁烷或環己基二噁烷、苯基-1,3-二噻或環己基-1,3-二噻、1,2-二苯基乙烷、1,2-二環己基乙烷、1-苯基-2-環己基乙烷、1-環己基-2-(4-苯基環己基)乙烷、1-環己基-2-聯苯乙烷、1-苯基-2-環己基苯基乙烷、視情況鹵化二苯乙烯、苄基苯基醚、二苯乙炔及經取代之肉桂酸。該等化合物中之1,4-伸苯基亦可經氟化。 適宜作為本發明介質之其他成分的最重要化合物之特徵可在於式1、2、3、4及5： R'-L-E-R" 1 R'-L-COO-E-R" 2 R'-L-CF2
O-E-R" 3 R'-L-CH2
CH2
-E-R" 4 R'-L-C≡C-E-R" 5 在式1、2、3、4及5中，L及E可相同或不同且各自彼此獨立地表示來自由以下結構要素所組成之群之二價基團：-Phe-、-Cyc-、-Phe-Phe-、-Phe-Cyc-、-Cyc-Cyc-、-Pyr-、-Dio-、-Py-、-G-Phe-、-G-Cyc-及其鏡像，其中Phe表示未經取代或經氟取代之1,4-伸苯基，Cyc表示反式-1,4-伸環己基，Pyr表示嘧啶-2,5-二基或吡啶-2,5-二基，Dio表示1,3-二噁烷-2,5-二基，Py表示四氫吡喃-2,5-二基且G表示2-(反式-1,4-環己基)乙基。 基團L及E中之一者較佳為Cyc、Phe或Pyr。E較佳為Cyc、Phe或Phe-Cyc。本發明介質較佳包含一或多種選自其中L及E係選自由Cyc、Phe及Pyr組成之群之式1、2、3、4及5之化合物的組分，及同時一或多種選自其中基團L及E中之一者係選自由Cyc、Phe、Py及Pyr組成之群且另一基團係選自由-Phe-Phe-、-Phe-Cyc-、-Cyc-Cyc-、-G-Phe-及-G-Cyc-組成之群之式1、2、3、4及5之化合物的組分，及視情況一或多種選自其中基團L及E係選自由-Phe-Cyc-、-Cyc-Cyc-、-G-Phe-及-G-Cyc-組成之群之式1、2、3、4及5之化合物的組分。 R'及/或R"各自彼此獨立地表示具有最多8個C原子之烷基、烯基、烷氧基、烷氧基烷基、烯氧基或烷醯基氧基、-F、-Cl、-CN、-NCS或-(O)i
CH3-k
Fk
，其中i係0或1且k係1、2或3。 在式1、2、3、4及5之化合物之較小子群中，R'及R"各自彼此獨立地表示具有最多8個C原子之烷基、烯基、烷氧基、烷氧基烷基、烯氧基或烷醯基氧基。此較小子群在下文中稱為群A，且化合物係由子式1a、2a、3a、4a及5a來提及。在大多數該等化合物中，R'及R"彼此不同，該等基團中之一者通常為烷基、烯基、烷氧基或烷氧基烷基。 在式1、2、3、4及5之化合物之另一較小子群(其稱為群B)中，R"表示-F、-Cl、-NCS或-(O)i
CH3-k
Fk
，其中i係0或1且k係1、2或3。其中R"具有此含義之化合物係由子式1b、2b、3b、4b及5b來提及。尤佳者係其中R"具有含義-F、-Cl、-NCS、-CF3
、-OCHF2
或-OCF3
之子式1b、2b、3b、4b及5b之彼等化合物。 在子式1b、2b、3b、4b及5b之化合物中，R'具有在子式1a至5a之化合物情形下所指示之含義且較佳係烷基、烯基、烷氧基或烷氧基烷基。 在式1、2、3、4及5之化合物的另一較小子群中，R"表示-CN。此子群在下文中稱為群C，且此子群之化合物相應地由子式1c、2c、3c、4c及5c所闡述。在子式1c、2c、3c、4c及5c之化合物中，R'具有在子式1a至5a之化合物情形下所指示之含義且較佳係烷基、烷氧基或烯基。 除群A、B及C之較佳化合物以外，具有所提議取代基之其他變化形式之式1、2、3、4及5之其他化合物亦慣用。所有該等物質皆可藉由自文獻已知之方法或以與其類似之方式獲得。 除本發明之式I化合物以外，本發明之介質較佳包含一或多種選自群A、B及/或C之化合物。在本發明之介質中，來自該等群之化合物之重量%較佳為： 群A： 0重量%至90重量%、較佳20重量%至90重量%、尤佳30重量%至90重量%； 群B： 0重量%至80重量%、較佳10重量%至80重量%、尤佳10重量%至65重量%； 群C： 0重量%至80重量%、較佳0重量%至80重量%、尤佳0重量%至50重量%； 其中，各別本發明介質中存在之群A、B及/或C化合物之重量%的總和較佳係5重量%至90重量%且尤佳係10重量%至90重量%。 本發明之介質較佳包含1重量%至40重量%、尤佳5重量%至30重量%之本發明之化合物。 本發明之液晶混合物係以本身習用之方式來製備。一般而言，將期望量之用量較少的組分較佳地在升高之溫度下溶解於構成主要成分之組分中。亦可在有機溶劑(例如，在丙酮、氯仿或甲醇中)中混合該等組分之溶液，且在徹底混合後再藉由(例如)蒸餾來去除溶劑。此外，可以其他習用方式製備混合物，例如藉由使用預混合物(例如，同系混合物)或使用所謂的「多瓶」系統。 電介質亦可包含熟習此項技術者已知且闡述於文獻中之其他添加劑。舉例而言，可添加0%至15%、較佳0%至10%之多色性染料、對掌性摻雜劑、穩定劑或奈米粒子。所添加之個別化合物係以0.01%至6%、較佳0.1%至3%之濃度使用。然而，液晶混合物(亦即液晶或液晶原化合物)之其他成分之濃度數據在此係在未考慮該等添加劑之濃度的情形下給出。 本發明之液晶混合物使能夠顯著擴展可用參數寬容度。 本發明亦關於含有此類型介質之電光顯示器(尤其TFT顯示器，其具有兩個連同框架一起形成單元之平面平行外板、在外板上用於切換個別像素之經整合非線性元件及位於單元中具有正介電各向異性及高比電阻之向列型液晶混合物)，及該等介質用於電光目的之用途。 表述「烷基」涵蓋具有1-9個碳原子之無支鏈及具支鏈烷基，特定而言無支鏈基團甲基、乙基、丙基、丁基、戊基、己基及庚基。具有2-5個碳原子之基團通常較佳。 表述「烯基」涵蓋具有最多9個碳原子之無支鏈及具支鏈烯基、尤其無支鏈基團。尤佳之烯基係C2
-C7
-1E-烯基、C4
-C7
-3E-烯基、C5
-C7
-4-烯基、C6
-C7
-5-烯基及C7
-6-烯基，尤其C2
-C7
-1E-烯基、C4
-C7
-3E-烯基及C5
-C7
-4-烯基。較佳烯基之實例係乙烯基、1E-丙烯基、1E-丁烯基、1E-戊烯基、1E-己烯基、1E-庚烯基、3-丁烯基、3E-戊烯基、3E-己烯基、3E-庚烯基、4-戊烯基、4Z-己烯基、4E-己烯基、4Z-庚烯基、5-己烯基、6-庚烯基及諸如此類。具有最多5個碳原子之基團通常較佳。 表述「鹵化烷基」較佳涵蓋單氟化或多氟化及/或氯化基團。包括全鹵化基團。尤佳者係氟化烷基、尤其CF3
、CH2
CF3
、CH2
CHF2
、CHF2
、CH2
F、CHFCF3
及CF2
CHFCF3
。表述「鹵化烯基」及相關表述相應地經解釋。 本發明混合物中式I化合物之總量並不重要。因此，出於最佳化各種性質之目的，混合物可包含一或多種其他組分。 自偏振器、電極基板及表面處理電極構造本發明之矩陣顯示器對應於用於此類型顯示器之常見設計。術語常見設計在此處係寬泛地描繪且亦涵蓋矩陣顯示器之所有衍生物及修改，尤其亦涵蓋基於多晶Si TFT之矩陣顯示元件。 然而，本發明顯示器與基於扭轉向列型單元之至今習用顯示器之間的顯著差異在於液晶層之液晶參數之選擇。 以下實例意欲闡釋本發明而非對其加以限制。熟習此項技術者將能夠自該等實例推斷出並未在一般說明中詳細給出之工作細節，依照一般專業知識對其進行歸納並將其應用至具體問題中。 在上下文中，百分比數據表示重量百分比。所有溫度係以攝氏度指示。此外，C =晶態，N =向列相，S =層列相且I =各向同性相。該等符號之間之數據代表轉變溫度。Δn表示光學各向異性(589 nm，20℃)，Δε表示介電各向異性(1 kHz，20℃)且γ1
表示旋轉黏度(20℃；單位為mPa·s)。 物理、物理化學及電光參數係藉由眾所周知之方法測定，如尤其手冊「Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurement Methods」，1998，Merck KGaA，Darmstadt中所述。 個別物質之介電各向異性Δε係在20℃及1 kHz下測定。為此，將量測溶解於介電正性混合物ZLI-4792 (Merck KGaA)中之5重量%至10重量%之欲研究物質，且將量測值外推至100%之濃度。光學各向異性Δn係在20℃及589.3 nm之波長下測定，旋轉黏度γ1
在20℃下測定，兩者同樣係藉由直線外推。 除非另外指示，否則在本申請案中，術語之複數形式表示單數形式及複數形式二者且反之亦然。根據說明之本發明之實施例及變化形式之其他組合亦由隨附申請專利範圍產生。 使用以下縮寫： MTB 甲基第三丁基醚 DCM 二 氯甲烷 LiHDMS 雙(三甲基矽基)醯胺鋰(LiN(SiMe3
)2
) DMPU 1,3-二甲基-3,4,5,6-四氫-2(1H
)-嘧啶酮 DBU 1,8-二氮雜二環[5.4.0]十一-7-烯實例 1.
4''-乙基-2'-氟-4-((E)-4-氟丁-3-烯基)-[1,1';4',1'']聯三苯步驟1：3-(4''-乙基-2'-氟-[1,1';4',1'']聯三苯-4-基)丙醛之合成將20 ml於水中之四氧化鋨(4%)添加至50 g (151 mmol)於1 l二噁烷/水(3:1)中之丁烯化合物，將混合物攪拌30 min，且然後以小份添加81 g (380 mmol)偏過碘酸鈉並將混合物攪拌2.5 h。在此期間，溫度暫時升高至約40℃。將0.5 l水及0.5 l乙酸乙酯添加至經冷卻之批料中，並分離各相。用水洗滌有機相。將有機相經硫酸鈉乾燥、過濾並在旋轉蒸發器中蒸發。藉由管柱層析(SiO2
，DCM)純化殘餘物並蒸發，從而得到呈灰色固體形式之產物(99% GC)。 步驟2：4''-乙基-2'-氟-4-((E)-4-氟丁-3-烯基)-[1,1';4',1'']聯三苯之合成將在先前反應中所獲得之30 g (0.09 mol)芳香族醛、19.7 g苯并噻唑(0.08 mol)及17.2 g DMPU (0.13 mol)初始在氮下引入450 ml無水THF中，並在-30℃下緩慢添加134 ml LiHDMS (1 M於己烷中，0.13 mol)。將批料進一步在冰浴中攪拌並在約24 h後藉由添加200 ml氯化銨水溶液、水及MTB醚進行處理。分離各相並將有機相經硫酸鈉乾燥、過濾並在旋轉蒸發器中蒸發。將棕色油狀殘餘物藉由管柱層析(SiO2
，庚烷/DCM = 8:2)純化，從而得到呈黃色油狀物形式之產物，其結晶析出(順式/=反式混合物，約1:1)。藉助製備型HPLC (乙腈/水)分離出順式部分。 獲得呈無色結晶針狀形式之期望產物。 C 58 N 161 I (m. p. 58℃) ∆ε = 8.4 ∆n = 0.272 γ1
= 153 mPa·s實例 2.
4-甲基-4'-((E)-5,5,5-三氟戊-3-烯基)聯苯步驟1：在0℃下將13.3 ml三氟甲基三甲基矽烷及然後150微升1 M四丁基氟化銨溶液(0.15 mmol)添加至於150 ml THF中之21 g (151 mmol)丁醛中。將混合物在冰浴中再攪拌1 h並在室溫下再攪拌12 h。 將水添加至批料，用MTB醚將混合物萃取兩次並分離各相。用水洗滌合併之有機相並經硫酸鈉乾燥、過濾並在旋轉蒸發器中蒸發。藉由管柱層析(SiO2
，庚烷/DCM 1:1)純化殘餘物並蒸發，從而得到呈固體形式之產物(95% GC)。 步驟2：將來自步驟1之全部產品初始引入180 ml THF中並在室溫下添加7.2 ml鹽酸水溶液(25%)。1 h後添加水並將混合物用MTB醚萃取兩次。用水洗滌合併之有機相並經硫酸鈉乾燥。經蒸發之溶液得到粗產物(97% GC)，其在矽膠上用乙腈/水純化(99.9% GC)。 步驟3：將來自步驟2之產物(21g)溶解於200 ml DCM中，並添加13 ml三乙胺及166 mg 4-(二甲基胺基)吡啶。將混合物冷卻至5℃並經約30 min之時期在溫度控制下(＜ 10℃)添加三氟甲磺酸酐(Tf2
O, 14 ml)。將混合物在室溫下攪拌12 h。將200 ml庚烷添加至反應混合物，其與庚烷/二氯甲烷一起直接在矽膠上穿過並藉由層析處理。 步驟4：將來自步驟3之產物(19.7 g)溶解於220 ml DBU中(放熱)並攪拌1 h。處理係藉由添加水並用MTB醚萃取來進行。使粗產物經矽膠於庚烷/二氯甲烷3:1中經受分級純化(96% GC)。純度藉由自乙醇及庚烷再結晶增加至＞ 99.5% (GC/HPLC)。 C 110 I (m. p. 110℃) ∆ε = 7.3 ∆n = 0.149 γ1
= 59 mPa·s 以下係以類似方式製備：實例 3.
4''-乙基-2'-氟-4-((E)-5,5,5-三氟戊-3-烯基)-[1,1';4',1'']聯三苯C 100 N 158 I ∆ε = +11.4 ∆n = 0.223 γ1
= 377 mPa·s實例 4.
4''-乙基-3,5,2'-三氟-4-((E)-4-氟丁-3-烯基)-[1,1';4',1'']聯三苯C 49 SmA 68 N 84 I ∆ε = +11.7 ∆n = 0.232 γ1
= 275 mPa·s實例 1 之起始化合物
4-丁-3-烯基-4''-乙基-2'-氟-[1,1';4',1'']聯三苯標題化合物係根據類似於自文獻已知之程序之反應方案，自所指示之化合物及試劑製備。 在第一步驟中，在回流下藉助於THF中之四(三苯基膦)鈀(約0.1%)及無水碳酸鈉(1當量)來實施鈴木偶合(Suzuki coupling)。 萃取純化後，使來自步驟1之產物直接在步驟2中與甲磺醯氯(1.5當量)及乙基二異丙基胺(1.3當量)在二氯甲烷中反應。水解及處理係藉由緩慢添加至比率3:2:1之冰、水及鹽酸之混合物(37%)並隨後利用二氯甲烷萃取。藉助矽膠過濾殘餘物。 在步驟3中，在0-5℃下將於THF中之烯丙基溴化鎂(1.4當量)添加至來自步驟2之氯化物及LiBr (1當量)。2 h後，添加水，將混合物過濾並用水及碳酸氫鈉溶液洗滌有機相。藉助矽膠過濾殘餘物並再結晶(m. p. 61℃)。 根據說明之本發明之實施例及變化形式之其他組合亦由以下申請專利範圍產生。The invention therefore relates to compounds of formula I, I wherein X represents F or CF 3 , m represents 1 or 2, preferably 1, R 1 represents a halogenated or unsubstituted alkyl group having 1 to 15 C atoms, and in addition, one of these groups or Multiple CH 2 groups can be independently of each other from -C≡C-, -CH = CH-,-(CO) O-, -O (CO)-,-(CO) -Or -O- substitution; or a polymerizable group, A represents a) 1,4-phenylene, in which one or two CH groups may be replaced by N, and in addition, one or more H atoms may be replaced by Br, Cl, F, CN, methyl, methoxy or monofluorinated or polyfluorinated methyl or methoxy substitution, b) trans-1,4-cyclohexyl or cyclohexenyl, wherein, in addition, One or more non-adjacent CH 2 groups may be replaced by -O- and / or -S- and wherein H may be replaced by F, Z 1 represents a single bond, -CH 2 O-,-(CO) O-, -CF 2 O-, -CH 2 CH 2 CF 2 O-, -CF 2 CF 2- , -CH 2 CF 2- , -CH 2 CH 2 -,-(CH 2 ) 4- , -CH = CH-, -CH = CF-, -CF = CF- or -C≡C-, where the asymmetric bridge can be oriented to both sides, L 1 and L 2 independently represent H or F, preferably H, and n represents 1, 2 Or 3. The invention further relates to the use of a compound of formula I in a liquid crystal medium. The invention also relates to a liquid crystal medium having at least two liquid crystal components, which include at least one compound of formula I. The compounds of formula I have a wide range of applications. Depending on the choice of substituents, these compounds can be used as the basic material of the liquid crystal medium; however, liquid crystal base materials from other types of compounds can also be added to the compounds of formula I to, for example, affect this type of dielectric Dielectric and / or optical anisotropy and / or optimize its threshold voltage and / or its viscosity. In the pure state, the compound of formula I is colorless and forms a liquid crystal mesophase by itself or in a mixture in a temperature range favorable for electro-optical applications. The compounds of the invention enable a wide range of nematic phases. In liquid crystal mixtures, the substances of the invention significantly increase the optical anisotropy and / or lead to an improvement in low-temperature storage stability compared to comparable compounds with high dielectric anisotropy. At the same time, the compounds are characterized by improved UV stability compared to materials known from the prior art that contain bridging elements between the rings (eg, -C≡C- or -CF = CF-). Z 1 in each case independently preferably represents a single bond, -CF 2 O-, -OCF 2- , -C 2 F 4- , -CH 2 O-, -OCH 2- , -C≡C-, or- (CO) O-, especially single bonds. A 1 is better And in addition or . R 1 preferably represents an alkyl, alkoxy, alkenyl or alkenyl or polymerizable group having up to 8 carbon atoms. R 1 particularly preferably represents an unbranched alkyl or alkenyl group having 1, 2, 3, 4, 5, 6, or 7 C atoms. R 1 very preferably represents ethyl or n-propyl. Occasionally, compounds of formula I containing branched or substituted wing-like groups R 1 may be important due to better solubility in conventional liquid crystal base materials. The group R 1 is preferably a straight chain. The substituent X preferably represents CF 3 . Preferred are compounds of formula I, wherein L 1 and L 2 represent a hydrogen atom. Preferred are compounds of formula I, wherein n is 2. Particularly preferred compounds of formula I are compounds of the formula: I1 I2 I3 I4 I5 I6 I7 I8 I9 I10 I11 I12 I13 I14 wherein X, m and R 1 independently have the meanings indicated above, especially their preferred meanings or combinations. Among the compounds of formulae I1 to I14, formulae I1, I2, I3, I8, I9, I10 and I11 are preferred, especially compounds of formulae I1 and I10 and I11. Especially preferred are illustrative compounds of the formula: Wherein R 1 is as defined above, and preferably represents an unbranched alkyl or alkenyl group having 1, 2, 3, 4, 5, 6, or 7 C atoms. Compounds of formula I are prepared by methods known per se, as described in the literature (for example in authoritative works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), exactly It is carried out under known reaction conditions suitable for such reactions. Variations known per se can also be used here, but are not mentioned in more detail here. The compounds of formula I can be obviously advantageously prepared from the following illustrative synthesis and examples (Schemes 1 and 2): Scheme 1. General synthetic scheme for the preparation of compounds of formula I (where X = F). Scheme 2 for preparing compounds of formula I (where X = CF 3) The general synthetic schemes. Corresponding starting materials can usually be easily prepared by those skilled in the art by synthetic methods known from the literature. The details of the reaction are revealed by working examples. The invention also relates to a liquid crystal medium comprising one or more compounds of formula I according to the invention. The liquid crystal medium contains at least two components. It is preferably obtained by mixing the components with each other. Therefore, the process of the present invention for preparing a liquid crystal medium is characterized in that at least one compound of formula I is mixed with at least one other mesogen compound, and additives are optionally added. The achievable combination of clarification point, viscosity at low temperature, thermal and UV stability, and dielectric anisotropy are excellently complementary to previous materials from the prior art. The liquid crystal medium of the present invention preferably contains 2 to 40, particularly preferably 4 to 30 components as components other than one or more compounds of the present invention. In particular, these media contain from 7 to 25 components in addition to one or more compounds of the invention. These other ingredients are preferably selected from nematic or nematogenic (monomorphic or isotropic) substances, in particular substances from the following categories: oxazobenzene, benzylideneaniline, biphenyl Benzene, bitriphenyl, phenyl benzoate or cyclohexyl benzoate, phenyl or cyclohexyl ester of cyclohexanecarboxylic acid, phenyl or cyclohexyl ester of cyclohexylbenzoic acid, cyclohexylcyclohexanecarboxylic acid Phenyl ester or cyclohexyl ester, benzoic acid, cyclohexane formic acid or cyclohexyl cyclohexane formic acid, cyclohexyl phenyl ester, phenyl cyclohexane, cyclohexyl biphenyl, phenyl cyclohexyl cyclohexane, cyclohexyl Hexylcyclohexane, cyclohexylcyclohexylcyclohexane, 1,4-dicyclohexylbenzene, 4,4'-bicyclohexylbiphenyl, phenylpyrimidine or cyclohexylpyrimidine, phenylpyridine or cyclohexylpyridine, phenyldi Oxane or cyclohexyldioxane, phenyl-1,3-dithia or cyclohexyl-1,3-dithia, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1 -Phenyl-2-cyclohexylethane, 1-cyclohexyl-2- (4-phenylcyclohexyl) ethane, 1-cyclohexyl-2-biphenylethane, 1-phenyl-2-cyclohexyl Phenylethane, optionally halogenated stilbene, benzylbenzene Ether, diphenylacetylene and substituted cinnamic acid. 1,4-phenylene in these compounds can also be fluorinated. The most important compounds suitable as other ingredients of the medium of the invention may be characterized by formulae 1, 2, 3, 4 and 5: R'-LER "1 R'-L-COO-ER" 2 R'-L-CF 2 OER "3 R'-L-CH 2 CH 2 -ER" 4 R'-LC≡CER "5 In formulas 1, 2, 3, 4 and 5, L and E may be the same or different and are each independently represented by each other Divalent group from the group consisting of the following structural elements: -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-,- Py-, -G-Phe-, -G-Cyc- and its mirror image, where Phe represents unsubstituted or fluorine-substituted 1,4-phenylene, Cyc represents trans-1,4-cyclohexyl, Pyr represents pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio represents 1,3-dioxane-2,5-diyl, and Py represents tetrahydropyran-2,5-diyl And G represents 2- (trans-1,4-cyclohexyl) ethyl. One of the groups L and E is preferably Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. The inventive medium preferably comprises one or more components selected from the group consisting of compounds of formulas 1, 2, 3, 4 and 5 where L and E are selected from the group consisting of Cyc, Phe and Pyr, and at the same time one or more components are selected from One of the groups L and E is selected from Cyc, Phe, Py, and Py a group consisting of r and another group selected from the group consisting of -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -G-Phe-, and -G-Cyc- Components of the compounds of 3, 4 and 5, and optionally one or more selected from the group in which the groups L and E are selected from -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc -A component of a group of compounds of formulae 1, 2, 3, 4 and 5. R 'and / or R "each independently represent an alkyl, alkenyl, alkoxy, Alkoxyalkyl, alkenyl or alkanoyloxy, -F, -Cl, -CN, -NCS or-(O) i CH 3-k F k , where i is 0 or 1 and k is 1 , 2 or 3. In the smaller subgroups of compounds of formulas 1, 2, 3, 4 and 5, R 'and R "each independently represent an alkyl, alkenyl, alkoxy, alkoxy group having up to 8 C atoms Alkyl, alkenyl, or alkynyloxy. This smaller subgroup is hereinafter referred to as Group A, and the compounds are mentioned by the formulae 1a, 2a, 3a, 4a, and 5a. In most of these compounds R 'and R "are different from each other, and one of these groups is usually an alkyl group, an alkenyl group, an alkoxy group, or an alkoxyalkyl group. In another smaller subgroup of compounds of formulas 1, 2, 3, 4 and 5 (which is referred to as group B), R "represents -F, -Cl, -NCS, or-(O) i CH 3-k Fk , where i is 0 or 1, and k is 1, 2 or 3. Compounds in which R "has this meaning are mentioned by sub-formulas 1b, 2b, 3b, 4b, and 5b. Particularly preferred are those compounds in which R "has the meanings -F, -Cl, -NCS, -CF 3 , -OCHF 2 or -OCF 3 , which are sub-formulae 1b, 2b, 3b, 4b and 5b. Among the compounds of 2b, 3b, 4b, and 5b, R ′ has the meaning indicated in the case of the compounds of sub-formulae 1a to 5a and is preferably an alkyl group, an alkenyl group, an alkoxy group, or an alkoxyalkyl group. In another smaller subgroup of the compounds of 1, 2, 3, 4 and 5, R "represents -CN. This subgroup is hereinafter referred to as group C, and the compounds of this subgroup are correspondingly described by sub-formulae 1c, 2c, 3c, 4c, and 5c. In the compounds of the sub formulae 1c, 2c, 3c, 4c and 5c, R ′ has the meaning indicated in the case of the compounds of the sub formulae 1a to 5a and is preferably an alkyl group, an alkoxy group or an alkenyl group. In addition to the preferred compounds of groups A, B and C, other compounds of formulas 1, 2, 3, 4 and 5 with other variations of the proposed substituents are also customary. All such substances can be obtained by methods known from the literature or in a similar manner. In addition to the compound of formula I according to the invention, the medium of the invention preferably comprises one or more compounds selected from the group A, B and / or C. In the medium of the present invention, the weight% of the compounds from these groups is preferably: Group A: 0% to 90% by weight, preferably 20% to 90% by weight, particularly preferably 30% to 90% by weight Group B: 0% to 80% by weight, preferably 10% to 80% by weight, particularly preferably 10% to 65% by weight; Group C: 0% to 80% by weight, preferably 0% to 80% % By weight, particularly preferably 0% by weight to 50% by weight; wherein the sum of the% by weight of each of the group A, B, and / or C compounds present in the medium of the present invention is preferably 5 to 90% by weight and particularly preferably 10% to 90% by weight. The medium of the present invention preferably contains 1 to 40% by weight, particularly preferably 5 to 30% by weight of the compound of the present invention. The liquid crystal mixture of the present invention is prepared in a conventional manner. In general, the desired amount of a lesser amount of a component is preferably dissolved in the components constituting the main component at an elevated temperature. It is also possible to mix solutions of these components in an organic solvent (for example, in acetone, chloroform or methanol), and after thorough mixing, remove the solvent by, for example, distillation. In addition, mixtures can be prepared in other conventional ways, such as by using a premix (eg, a homologous mixture) or using a so-called "multi-bottle" system. The dielectric may also contain other additives known to those skilled in the art and described in the literature. For example, 0% to 15%, preferably 0% to 10% of a polychromic dye, a palmate dopant, a stabilizer, or a nanoparticle may be added. The individual compounds added are used at a concentration of 0.01% to 6%, preferably 0.1% to 3%. However, the concentration data of the other components of the liquid crystal mixture (ie, the liquid crystal or the mesogen compound) are given here without considering the concentration of these additives. The liquid crystal mixture of the present invention enables a significant expansion of the available parameter latitude. The present invention also relates to an electro-optical display (especially a TFT display) containing this type of medium, which has two plane-parallel outer plates forming a unit together with a frame, an integrated non-linear element for switching individual pixels on the outer plate, and Nematic liquid crystal mixtures of positive dielectric anisotropy and high specific resistance), and the use of these media for electro-optical purposes. The expression "alkyl" encompasses unbranched and branched alkyl groups having 1 to 9 carbon atoms, specifically unbranched groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl base. Groups having 2-5 carbon atoms are generally preferred. The expression "alkenyl" encompasses unbranched and branched alkenyl groups, especially unbranched groups, having up to 9 carbon atoms. Particularly preferred alkenyl groups are C 2 -C 7 -1E-alkenyl, C 4 -C 7 -3E-alkenyl, C 5 -C 7 -4-alkenyl, C 6 -C 7 -5-alkenyl and C 7 -6-alkenyl, especially C 2 -C 7 -1E-alkenyl, C 4 -C 7 -3E-alkenyl and C 5 -C 7 -4-alkenyl. Examples of preferred alkenyl are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl , 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like . Groups having up to 5 carbon atoms are generally preferred. The expression "halogenated alkyl" preferably covers mono- or polyfluorinated and / or chlorinated groups. Includes perhalogenated groups. Particularly preferred are fluorinated alkyl groups, especially CF 3 , CH 2 CF 3 , CH 2 CHF 2 , CHF 2 , CH 2 F, CHFCF 3 and CF 2 CHFCF 3 . The expression "halogenated alkenyl" and related expressions are interpreted accordingly. The total amount of the compound of formula I in the mixture of the invention is not important. Therefore, for the purpose of optimizing various properties, the mixture may include one or more other components. Self Polarizer, Electrode Substrate, and Surface Treatment Electrode Construction The matrix display of the present invention corresponds to a common design for this type of display. The term common design is described here broadly and also covers all derivatives and modifications of the matrix display, especially the matrix display element based on polycrystalline Si TFT. However, a significant difference between the display of the present invention and the conventional display based on torsion nematic cells is the choice of liquid crystal parameters of the liquid crystal layer. The following examples are intended to illustrate the invention without limiting it. Those skilled in the art will be able to infer from these examples the details of work that are not detailed in the general description, summarize them in accordance with general expertise and apply them to specific problems. In the context, percentage data represents weight percent. All temperatures are indicated in degrees Celsius. In addition, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperature. Δn represents the optical anisotropy (589 nm, 20 ℃), Δε denotes the dielectric anisotropy (1 kHz, 20 ℃) and represents a rotational viscosity γ 1 (20 ℃; unit is mPa · s). Physical, physical chemistry and electro-optical parameters are determined by well-known methods, as described in the special manual "Merck Liquid Crystals-Licristal®-Physical Properties of Liquid Crystals-Description of the Measurement Methods", 1998, Merck KGaA, Darmstadt. The dielectric anisotropy Δε of individual substances is measured at 20 ° C and 1 kHz. To this end, the substance to be studied which is dissolved in a dielectric positive mixture ZLI-4792 (Merck KGaA) is measured in an amount of 5 to 10% by weight, and the measured value is extrapolated to a concentration of 100%. The optical anisotropy Δn is measured at 20 ° C and a wavelength of 589.3 nm, and the rotational viscosity γ 1 is measured at 20 ° C. The two are also extrapolated by a straight line. Unless otherwise indicated, in this application, the plural form of a term means both the singular form and the plural form and vice versa. Other combinations of embodiments and variations of the invention according to the description also result from the scope of the accompanying patent application. The following abbreviations are used: MTB methyl tert-butyl ether DCM dichloromethane LiHDMS lithium bis (trimethylsilyl) phosphonium amine (LiN (SiMe 3 ) 2 ) DMPU 1,3-dimethyl-3,4,5 4,6-tetrahydro-2 (1 H ) -pyrimidinone DBU 1,8-diazabicyclo [5.4.0] undec-7-ene Example 1. 4 ''-ethyl-2'-fluoro- 4-((E) -4-fluorobut-3-enyl)-[1,1 ';4', 1 ''] bitriphenyl Step 1: Synthesis of 3- (4``-ethyl-2'-fluoro- [1,1 ';4', 1 ''] bitriphenyl-4-yl) propanal 20 ml of osmium tetroxide (4%) in water was added to 50 g (151 mmol) of the butene compound in 1 l of dioxane / water (3: 1), the mixture was stirred for 30 min, and then 81 g (380 mmol) of sodium metaperiodate were added in portions and the mixture was stirred for 2.5 h. During this time, the temperature rose temporarily to about 40 ° C. 0.5 l of water and 0.5 l of ethyl acetate were added to the cooled batch, and the phases were separated. The organic phase was washed with water. The organic phase was dried over sodium sulfate, filtered and evaporated on a rotary evaporator. By column chromatography (SiO 2, DCM) and evaporated The residue was purified to give the product as a gray solid (99% GC). Step 2: 4``-Ethyl-2'-fluoro-4-((E) -4-fluorobut-3-enyl)-[1,1 ';4', 1 ''] bitriphenyl synthesis 30 g (0.09 mol) of the aromatic aldehyde obtained in the previous reaction, 19.7 g of benzothiazole (0.08 mol), and 17.2 g of DMPU (0.13 mol) were initially introduced into 450 ml of anhydrous THF under nitrogen, and at -30 Slowly add 134 ml of LiHDMS (1 M in hexane, 0.13 mol) at ° C. The batch was further stirred in an ice bath and treated after about 24 h by adding 200 ml of an aqueous ammonium chloride solution, water and MTB ether. The phases were separated and the organic phase was dried over sodium sulfate, filtered and evaporated on a rotary evaporator. The brown oily residue was purified by column chromatography (SiO 2 , heptane / DCM = 8: 2) to obtain the product in the form of a yellow oil, which crystallized out (cis / = trans mixture, John 1: 1). The cis fraction was separated by means of preparative HPLC (acetonitrile / water). The desired product is obtained in the form of colorless crystalline needles. C 58 N 161 I (mp 58 ° C) Δε = 8.4 Δn = 0.272 γ 1 = 153 mPa · s Example 2. 4-methyl-4 '-((E) -5,5,5-trifluoropentane -3-alkenyl) biphenyl step 1: 13.3 ml of trifluoromethyltrimethylsilane and then 150 μl of a 1 M solution of tetrabutylammonium fluoride (0.15 mmol) were added to 21 g (151 mmol) of butyraldehyde in 150 ml of THF at 0 ° C. The mixture was stirred for another 1 h in an ice bath and for another 12 h at room temperature. Water was added to the batch, the mixture was extracted twice with MTB ether and the phases were separated. The combined organic phases were washed with water and dried over sodium sulfate, filtered and evaporated on a rotary evaporator. By column chromatography (SiO 2, heptane / DCM 1: 1) and evaporated The residue was purified to give the product as a solid (95% GC). Step 2: The entire product from step 1 was initially introduced into 180 ml of THF and 7.2 ml of a hydrochloric acid aqueous solution (25%) was added at room temperature. After 1 h water was added and the mixture was extracted twice with MTB ether. The combined organic phases were washed with water and dried over sodium sulfate. The evaporated solution gave the crude product (97% GC), which was purified on silica gel with acetonitrile / water (99.9% GC). Step 3: The product from step 2 (21 g) was dissolved in 200 ml of DCM, and 13 ml of triethylamine and 166 mg of 4- (dimethylamino) pyridine were added. The mixture was cooled to 5 ° C and triflic anhydride (Tf 2 O, 14 ml) was added under temperature control (<10 ° C) over a period of about 30 minutes. The mixture was stirred at room temperature for 12 h. 200 ml of heptane was added to the reaction mixture, which was passed directly on silica together with heptane / dichloromethane and processed by chromatography. Step 4: The product from step 3 (19.7 g) was dissolved in 220 ml DBU (exothermic) and stirred for 1 h. The treatment was performed by adding water and extracting with MTB ether. The crude product was subjected to fractional purification (96% GC) over silica in heptane / dichloromethane 3: 1. Purity was increased to> 99.5% (GC / HPLC) by recrystallization from ethanol and heptane. C 110 I (mp 110 ℃) Δε = 7.3 Δn = 0.149 γ 1 = 59 mPa · s The following was prepared in a similar manner: Example 3. 4``-ethyl-2'-fluoro-4-((E ) -5,5,5-trifluoropent-3-enyl)-[1,1 ';4', 1 ''] bitriphenyl C 100 N 158 I Δε = +11.4 Δn = 0.223 γ 1 = 377 mPa · s Example 4. 4``-Ethyl-3,5,2'-trifluoro-4-((E) -4- (Fluorobut-3-enyl)-[1,1 ';4', 1 ''] bitriphenyl C 49 SmA 68 N 84 I Δε = Δn = 0.232 γ 1 = 275 mPa · s +11.7 Example 1 of the starting compound 4-but-3-enyl-4 '' - ethyl-2'-fluoro - [1,1 ';4', 1``] bitriphenyl The title compound was prepared from the indicated compounds and reagents according to a reaction scheme similar to procedures known from the literature. In the first step, Suzuki coupling was performed under reflux with the aid of tetrakis (triphenylphosphine) palladium (about 0.1%) and anhydrous sodium carbonate (1 equivalent) in THF. After extraction and purification, the product from step 1 was directly reacted in step 2 with methanesulfonyl chloride (1.5 equivalents) and ethyldiisopropylamine (1.3 equivalents) in dichloromethane. The hydrolysis and treatment were performed by slowly adding to a mixture of ice, water and hydrochloric acid (37%) in a ratio of 3: 2: 1 and then extracting with dichloromethane. Filter the residue with the help of silicone. In step 3, allyl magnesium bromide (1.4 equivalents) in THF will be added to the chloride and LiBr (1 equivalent) from step 2 at 0-5 ° C. After 2 h, water was added, the mixture was filtered and the organic phase was washed with water and sodium bicarbonate solution. The residue was filtered by means of silica gel and recrystallized (mp 61 ° C). Other combinations of the embodiments and variations of the invention according to the description also result from the scope of the following patent applications.