Materiais moleculares funcionais contendo n-heterociclos - capes

384 R. Cristiano et al.Scheme 2. Reagents: a. 1) 2-methyl-3-butyn-2-ol, PdCl 2 (PPh 3 ) 2 , CuI, TPP, TEA; 2) NaOH, toluene; b. PdCl 2 (PPh 3 ) 2 , CuI, TPP,TEA/THF; c. 4-decyloxybenzoic acid, DCC, DMAP, CH 2 Cl 2 .changes slowly at 188.2uC to schlieren SmC with aclearly visible fingerprint region between the twophases, characterizing a N–SmC transition. From thismesophase at 130.7uC there is a transition to anothersmectic phase, unidentified SmX, in which the texturechange is almost impossible to perceive by opticalmicroscopy, but it is easily established by DSC analysis.Representative textures obtained by optical microscopyfor these compounds are shown in figure 2.All the nematic phases present a schlieren textureTable 2. Thermal behaviour of compounds 1–7.Compound Transition T/uC, heating (DH/kJ mol 21 ) a T/uC, cooling (DH/kJ mol 21 ) a T dec. /uC b1 Cr–N 143.4 (35.3) 131.6 (234.2) 409N–I 159.7 (0.26) 158.7 (20.26)2 CrI–CrII 116.1 (7.92) 105.0 (27.44) 438CrII–(SmC) 125.8 (219.3)(SmC)–N 131.6 (23.1) 128.4 (20.29)N–I 156.3 (0.67) 152.2 (20.66)3 CrI–CrII 106.4 (3.7) 436CrII–CrIII 126.0 (7.0)CrIII–SmC 133.3 (2.3) 121.0 (211.7)SmC–N 140.1 (broad) 135.9 (20.35)N–I 153.5 (0.78) 152.9 (20.73)4 CrI–CrII 157.7 (34.1) 475CrII–CrIII 180.9 (7.08)Cr–SmC 221.9 (16.9) 214.20 (214.4)SmC–N 224.6 (broad) 223.4 (20.02)N–I 235.4 (broad) 232.8 (20.11)5 CrI–CrII 110.5 (16.8) 432CrII–CrIII 127.2 (7.51)CrIII–CrIV 141.7 (2.32)CrIV–SmC 150.1 (32.4) 126.8 (230.1)SmC–N 163.7 (0.11) 160.8 (20.16)N–I 197.8 (1.04) 194.9 (21.21)6 CrI–CrII 126.2 (9.87) 397CrII–SmC 141.1 (0.43) 101.8 (22.42)SmC–SmA 161.8 (1.67) 159.1 (23.41)SmA–N 221.9 (broad) 220.6 (22.11)N–I 231.5 (broad) 230.8 (20.13)7 CrI–CrII 96.65 (18.0) 433CrII–SmX 129.1 (33.4) 115.9 (216.2)SmX–SmC 143.0 (0.81) 130.7 (23.46)SmC–N 189.3 (1.03) 188.2 (20.97)N–I 239.3 (1.91) 237.8 (20.87)a Determined by optical microscopy and DSC measurements (10uC). b Determined by TGA, onset of decomposition in nitrogen(20uC min 21 ).