Sains Malaysiana, 2018;47:741-747.

Abstract

A benzoylthiourea molecule namely 1,1-dibenzyl-3-(2-bromobenzoyl)thiourea (2BrBT) was synthesized and characterized
by C, H, N and S elemental, mass spectrometry and spectroscopic analyses (infrared, ultraviolet-visible and nuclear
magnetic resonance). The 2BrBT compound crystallized in a tetragonal system with the space group P43 and exhibits
an acentric crystalline packing due to the presence of intermolecular H-bonding network that forms a self-assembly
of 1D helical motif. The asymmetric delocalisation of electrons in the molecule retains its transparency throughout the
visible and near-infrared region and hence, essentially propagates the macroscopic helical motif in the solid state. The
highest-occupied and lowest-unoccupied molecular orbital (HOMO/LUMO) are mainly found on the thiourea moiety and
the benzoylthiourea fragment, respectively and shows an optical bandgap of 3.50 eV. The influence of its geometrical
characteristics to the optical properties of 2BrBT is established and discussed in view of nonlinear optical (NLO)
application.