Organometallic-organic hybrid crystals from ferrocenyl dipyridine and binaphthol: Different crystal structures and nonlinear optical properties depending upon the reaction medium and optical purity of binaphthol

Abstract

The hydrogen bond directed molecular recognition between 1,1'-bis(ethenyl-4-pyridyl)ferrocene (1) and (+/-)-1,1'-binaphthol (2)/(-)-1,1'-binaphthol ((-)-2) has been studied by cocrystallization in different solvents. Single-crystal X-ray structures reveal that 3:2, 2:1, and 1:1 complexes (3, 4, and 5, respectively) of 1,1'-bis(ethenyl-4-pyridyl)ferrocene (1) and (+/-)-1,1-binaphthol (2) are formed in tetrahydrofuran, methanol, and ethanol, respectively. 5 has a noncentrosymmetric packing arrangement, and an efficiency of 0.3 times that of urea in second-harmonic generation has been measured at 1295 nm. An X-ray crystal structure of 6, 1:1 complex of 1 with (-)-2 in ethanol, reveals that all the molecular dipoles are aligned in the same direction (i.e, a polar crystal), but 6 has modest nonlinear optical properties (ca. 0.4 times that of urea).