Polar diphenyldiacetylene liquid crystals

A eutectic mixture of liquid crystal compounds comprising at least two liquid crystal compounds including at least one diphenyldiacetylene liquid crystal compound having the general structure:

• wherein
• R1 is selected from the group consisting of alkenyl groups having the general formula (CnH2n−1) wherein n ranges approximately from 2 to 12;
• X is independently selected from the group consisting of CN, F, CF3, OCF3, and Cl;
• Y1 is independently selected from the group consisting of H, F, Cl, and CH3;
• Y2 is independently selected from the group consisting of H, F, Cl, and CH3;
• Z1 is independently selected from the group consisting of H, F, and CH3;
• and
• Z2 is independently selected from the group consisting of H, F, and CH3.

A method for preparing diphenyldiacetylene liquid crystal compounds, comprising the steps of:

• i. reacting a brominated phenyl alcohol as shown in Structure I with a brominating agent to produce a dibromide as shown in Structure II:
• wherein Z1 on both structures is from the group consisting of H, F, and CH3 and Z2 on both structures is from the group consisting of H, F, and CH3 and n ranges from 0 to approximately 10;
• ii. isolating the dibromide of Structure II from the reaction of the brominated phenyl alcohol of Structure I and a brominating agent;
• iii. reacting the dibromide of Structure II with triphenylphosphine to produce the tetraorganophosphonium salt shown in Structure III:
• wherein Z1 is H, F, or CH3, and Z2 is H,F, or CH3 and n ranges approximately from 0 to 10;
• iv. isolating the salt of structure III from the reaction of the dibromide of Structure II with triphenylphosphine;
• v. reacting the salt of structure III with an aldehyde having the formula RCHO wherein R is an alkyl substituent having the general formula (CxH2x+1) wherein x ranges from 0 to approximately 10, and a catalyst to produce the compound shown in Structure IV:
• wherein Z1 is from the group consisting of H, F, and CH3, Z2 is from the group consisting of H, F, and CH3, R is an alkyl group having the formula (CxH2x+1) wherein x ranges from 0 to approximately 10, n ranges from 0 to approximately 10, and x+n is less than or equal to about 10;
• vi. isolating the compound of Structure IV from the reaction of the salt of Structure III with and an aldehyde;
• vii. reacting the compound of Structure IV with a protected 1-alkyne in the presence of a catalyst under an inert atmosphere to give the protected acetylene shown in Structure V:
• wherein Z1 is H, F, or CH3, Z2 is H, F, or CH3, R is an alkyl group having the formula (CxH2x+1) wherein x ranges from 0 to approximately 10, n ranges from 0 to approximately 10, and x+n is less than or equal to about 10;
• viii. isolating the protected acetylene of Structure V from the reaction of the compound of Structure IV and a protected 1-alkyne in the presence of presence of a catalyst under an inert atmosphere;
• ix. unprotecting the protected acetylene of Structure V with base to produce the acetylene shown in Structure VI:
• wherein Z1 is H, F, or CH3, Z2 is H, F, or CH3, R is an alkyl group having the formula (CxH2x+1) wherein x ranges from 0 to approximately 10, n ranges from 0 to approximately 10 and x+n is less than or equal to about 10;
• x. isolating the acetylene in Structure VI from the reaction of the acetylene of Structure V and base;
• xi. reacting the benzaldehyde shown in Structure IX with triphenylphosphine and a catalyst to produce the bromostyryl compound shown in Structure X:
• wherein X is selected from the group consisting of CN, F, CF3, OCF3, and Cl, Y1 is selected from the group consisting of H, F, and Cl, and Y2 is selected from the group consisting of H, F, and Cl;
• xii. isolating the dibromostyryl compound of Structure X from the reaction of Structure IX with triphenylphosphine and a catalyst;
• xiii. reacting the dibromostyryl compound of Structure X with t-butoxide to produce the bromoacetylide shown in Structure VII;
• wherein X is CN, F, CF3, OCF3, or Cl, Y1 is H, F, or Cl, and Y2 is H, F, or Cl;
• xiv. isolating the bromoacetylide of Structure VII from the reaction of the dibromostyryl compound of Structure X and t-butoxide;
• xv. reacting the acetylene of Structure VI with the bromoacetylide of Structure VII in the presence of a copper(I)salt and an amine in an inert atmosphere to produce the diacetylene shown in Structure VIII:
• wherein X is selected from the group consisting of CN, F, CF3, OCF3, and Cl, Y1 is selected from the group consisting of H, F, and Cl, Y2 is selected from the group consisting of H, F, and Cl, Z1 is selected from the group consisting of H, F, and CH3, Z2 is selected from the group consisting of H, F, and CH3, R is an alkyl group having the general formula (CxH2x+1) wherein x ranges from 0 to approximately 10, n ranges from 0 to approximately 10, and x+n is less than or equal to about 10;
• xvi. isolating the diacetylene of Structure VIII from the reaction of the acetylene of Structure VI with the bromoacetylide of Structure VII in the presence of a copper(I) salt and an amine in an inert atmosphere.