The role of solvents in framework dimensionality and their effect on band gap energyElectronic supplementary information (ESI) available: Theoretical calculations, crystallographic parameters, selected bond lengths, characteristics IR data, TOPOS analysis, ORTEP diagrams, figures for structures, emission spectra, PXRD, TGA, IR, band gap energy. CCDC 1007066-1007067. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4dt01678e

• Main Authors: Asha, K. S, Kavyasree, P. R, George, Anu, Mandal, Sukhendu
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c4dt01678e

The crystal growth rate and morphology can be modulated by tuning the ratio of the solvent in mixed solvents during synthesis. We present here a solvothermal method to synthesize a Cd-FDC based metal-organic framework with different morphologies by tuning the ratio of water in the DMF-water mixed solvent system without adding any other additives. With the increasing water volume ratio a series of crystals with different morphologies were synthesized. Among these we have isolated two single crystal structures, [Cd 3 (FDC) 3 (DMF) 4 (H 2 O)], 1 and [DMA] 2 [Cd 3 (FDC) 4 ]·2H 2 O, 2 . Compound 1 was synthesized from DMF with small amounts of water while 2 was formed from 25 vol% of water in the DMF-water mixed solvent. Compound 1 contains trimer clusters as building units, which are linked by the furan dicarboxylate ligand to form a two-dimensional structure. Compound 2 also contains trimer clusters which are linked to each other to form a one-dimensional chain with the Cd-O-Cd linkage. This one-dimensional chain in turn is connected by the furan dicarboxylate ligand to form a three-dimensional structure. All these structures are characterized by SEM, XRD, TGA and IR. We have measured the band gap energy and measurements show that the values are decreasing from 1 to 2 . The lower band gap energy of 2 may be due to the presence of infinite Cd-O-Cd linkages which split the states of the conduction band and reduces the band gap energy. Solvents play a crucial role towards the dimensionality and band gap energy of hybrid framework materials.