Structures and nonlinear optical properties of molecular crystals DMCC and DBCC

Structures and nonlinear optical properties of dimethylcroconate (DMCC) and dibenzoylcroconate (DBCC) are reported. The SHG active DMCC crystal packed in non-centrosymmetric P212121 space group. The DBCC crystal has a host–guest structure and crystallized in centrosymmetric P21/n space group. In DBCC crystal, the host DBCC molecules build channels along the b direction with the guest benzene molecules trapped in the channels. DSC, XRD, SHG and structural studies reveal that these benzene molecules can be removed at 90 °C, accompanying the loss of the centro-symmetry and resulting in the SHG active new crystalline phase.