Crystal engineering is a synthetic endeavour that begins with the synthesis or identification of suitable molecular building blocks which can be combined in a directed manner by self-assembly methods to yield interesting and practical crystalline products (Braga et al., 2005). A common feature of such design approaches is to employ polyfunctional organic ligands such as dicarboxylic acids and combine them with N-heterocycle and polyoxometalate (POMs) co–ligands to prepare crystalline coordination compounds and hybrid organic-inorganic polyoxometalates respectively (Mirzaei et al., 2014, 2011, Taleghani et al., 2016). These crystal structures have high structural stability and infinite variety of unique chemical, physical, and biological properties. Due to importance of this field, a novel series of proton transfer coordination compounds and inorganic-organic hybrid architectures based on dicarboxylate/N-heterocycle bases and dicarboxylate/POMs have been synthesized under mild, hydrothermal and sonochemical conditions (Mirzaei et al., 2014, 2016). From the viewpoint of crystal engineering, the control of the dimensionality of the resulting compounds is still a great challenge, as the final structures are frequently modulated by various factors. The objective of the present speech is to explore the effect of organic ligands, POMs charge density, size and type of the metal ions and synthetic conditions in final frameworks. Also, the luminescent, medicinal, magnetic and gas storage properties of some of these compounds have been investigated.

Keywords