NLO crystals of bis[1-(diaminomethylene)thiouron-1-ium] tartate(2 -) hemihydrate and deuterated [1-(diaminomethylene)thiouron-1-ium] tartate(- ).

Abstract

The protiated single crystals of bis[1-(diaminomethylene)thiouron-1-ium] tartate hemihydrate were grown using a solution growth technique. The deuterated single crystals of [1-(diaminomethylene)thiouron-1-ium] tartate(_) were obtained by threefold recrystallisation of protiated crystals. The protiated and deuterated compounds crystallise in the non-centrosymmetric space groups P21212 and P21 of the orthorhombic and monoclinic systems, respectively. The conformation of the 1-(diaminomethylene)thiouron-1-ium cation in both structures is very similar and is almost planar. The double deprotonated tartate(2_) dianion in protiated crystals exhibits C2 symmetry, while tartate(_) monoanion in deuterated crystals has C1 symmetry. The oppositely charged components of the crystals, i.e. 1-(diaminomethylene)thiouron-1-ium cation and tartate(2_) dianion in protiated and 1-(diaminomethylene)thiouron-1-ium cation and tartate(_) monoanion, interact via different hydrogen bonding motifs: R12 (6) and R22 (8) in protiated and R21 (5) and R12 (6) in deuterated crystals forming 2:1 and 1:1 supramolecular complexes. These supramolecular complexes interact each other via NAH_ _ _O or OAH_ _ _O hydrogen bonds forming the 2D-layered structures. Both compounds were also characterised by IR-spectroscopy. The SHG efficiency relative to potassium dihydrophosphate (KDP) was found to be 0.77 and 0.82 for protiated and deuterated crystals, respectively.