2D frameworks of Cu(II) and Zn(II) organo-metallic polymers self-assembled with N,N′-(1,2-phenylene)diisonicotinamide: Syntheses, structures, photoluminescence, and thermal properties

Reaction of the ligand N,N′-(1,2-phenylene)diisonicotinamide (pia) with metal(II) salts MSO4 [M = Cu(II), Zn(II)] leads to the formation of two 2D coordination networks [(CuSO4)(pia) · 2CH3OH · H2O]n (1) and [(ZnSO4)(pia) · 2H2O]n (2). In the solid state of 1 the Cu(II) center adopt a five-coordination square pyramidal geometry, and the network is generated through the interconnection of the pia organic moieties by [Cu2(SO4)2] dimers resulting in a 2D motif containing irregular inner cavities for guest molecule inclusion; in the case of 2, the Zn(II) center adopt a tetrahedral coordination geometry and the 2D network is formed by pia with another type of connector, zigzag SO 4 2 - –Zn chains. Compound 2 displays intense photoluminescence in the solid state at room temperature upon photo-excitation at 245 nm. The photoluminescence behaviors of the polymer 2 are related to the intraligand emission excited state.