HYDROGEN-BOND-DIRECTED SELF-ASSEMBLY OF D-(-DIBENZOYL TARTARIC ACID AND 4-AMINOPYRIDINE - OPTICAL NONLINEARITIES AND STOICHIOMETRY-DEPENDENT NOVEL STRUCTURAL FEATURES())

Attempts to prepare hydrogen-bond-directed nonlinear optical materials from a 1:1 molar mixture Of D-(+)-dibenzoyltartaric acid (DBT, I) and 4-aminopyridine (4-AP, II) resulted in two salts of different stoichi ometry. One of them crystallizes in an unusual 1.5:1 (acid:base) monoh ydrate salt form III while the other one crystallizes as 1:1 (acid:bas e) salt IV. Crystal structures of both of the salts were determined fr om single-crystal X-ray diffraction data. The salt III crystallizes in a monoclinic space group C2 with a = 30.339(l), b = 7.881(2), c = 14. 355(1) angstrom, beta = 97.48(1)degrees, V = 3403.1(9) angstrom3, Z = 4, R(w) = 0.058, R(w)= 0.058. The salt IV also crystallizes in a monoc linic space group P2(1) with a = 7.500(1), b = 14.968(2), c = 10.370(1 ) angstrom, beta = 102.67(1)degrees, V = 1135.9(2) angstrom3, Z = 2, R = 0.043, R(w) = 0.043. Interestingly, two DBT molecules with distinct ly different conformation are present in the same crystal lattice of s alt III. Extensive hydrogen-bonding interactions are found in both of the salts, and both of them show SHG intensity 1.4-1.6 times that of u rea.