Possible Application of the Organic Barbiturates as NLO Materials

The self-assembly, crystal structures, and optical properties are reported for eight novel organic crystals of derivatives of barbituric acid, i.e. 4-methoxypyrydinium barbiturate dihydrate ( 1 ), 1,10-phenanthrolinium barbiturate monohydrate ( 2 ), 1-amino isoquinolinium barbiturate monohydrate ( 3 ), 5-hydrohy- L -tryptophan barbituric acid complex ( 4 ), 5-hydroxy- L -tryptophan 1,3-dimethylbarbituric acid dihydrate molecule complex ( 5 ), 1,10-phenanthrolinium ( thio )barbiturate ( 6 ), 1-amino-1,2,4-triazole violuric acid monohydrate ( 7 ), and pyridine-3-aldoxime violuric acid complex ( 8 ). Compounds 1 − 8 were synthesized and characterized by means of single crystal X-ray diffraction, solution and solid-state UV/vis/NIR spectroscopy, and linear-polarized infrared (IR-LD) spectroscopy. Quantum chemical ab initio and DFT calculations were performed with a view to understanding the optical properties of these species. The potential application of these derivatives as NLO-phores is discussed by comparison with the corresponding violurate salts.