Synthesis optimisation and characterisation of the organic-inorganic layered materials ZnS(m-xylylenediamine)(1/2) and ZnS(p-xylylenediamine)(1/2)

Abstract Hybrid organic-inorganic layered materials of the type ZnS(amine) 1/2 , where amine= m -xylylenediamine (MXDA) or p -xylylenediamine (PXDA), were synthesised using a simple solvothermal method. Since the samples crystallised in the form of very fine powder, X-ray powder diffraction techniques were used for structural characterisation. The crystal structure studies, involving direct methods, show that both compounds crystallised in the orthorhombic crystal system, but in different space groups: ZnS(MXDA) 1/2 in non-centrosymmetric Ccm2 1 , ZnS(PXDA) 1/2 in centrosymmetric Pcab. The obtained materials are built according to similar orders: semiconducting monolayers with the formula ZnS, parallel to the (010) plane, are separated by diamines. The organic and inorganic fragments are connected by covalent bonds between metal atoms of the layers and nitrogen atoms of the amino groups. The optical properties of the hybrid materials differ from those of their bulk counterpart. In both compounds a blue-shift of about 0.8 or 0.9 eV was observed with reference to the bulk phase of ZnS.