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Three cadmium(II) coordination polymers, namely {[Cd(HLI)(NO3)2]·0.5MeOH}n (1), {[Cd(HLII)(NO3)2]·EtOH}n (2), and [Cd2(LII)2(NO3)2]n (3), have been self-assembled from Cd(NO3)2 and N,N′,O-pincer-type isonicotinoylhydrazone-based ditopic ligands (HLI = N′-(pyridin-2-ylmethylene)isonicotinohydrazide and HLII = N′-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide) and have been characterized experimentally and by DFT computations. In compounds 1 and 2, the corresponding ligand is coordinated to the metal center in the keto form and acted as a tetradentate chelating–bridging agent in which the nitrogen atom of the 4-pyridine ring is coordinated to the cadmium center of the neighboring unit, yielding 1D zig-zag coordination polymers. In compound 3, the ligand was singly-deprotonated and is coordinated in the enolic form with the nitrate ion further acted as a bridging agent, yielding a 2D network. It is revealed by the extended transition state natural orbital for chemical valence (ETS-NOCV) charge and energy decomposition scheme that typical hydrogen bonds O–H⋯O and N–H⋯O, which constitute the networks of 1 and 2, though dominated by a classic Coulomb term, are characterized by an equally important London dispersion constituent due to extra π⋯π and C–H⋯X contacts (X = O, H–C, H–N). The architecture of 3 is due to ionic and dative-covalent Cd–X (X = N, O) bonds as well as London dispersion-driven homopolar dihydrogen C–H⋯H–C and C–H⋯O interactions. NOCV-based representation allowed us to determine that hydrogen bonds O–H⋯O are twice weaker than the corresponding N–H⋯O in the networks of 1 and 2. [ABSTRACT FROM AUTHOR]

The emergence of new infectious diseases and their high mortality rate reveals the need for more attention to this area and the synthesis of new compounds. In this work, two mixed ligand cadmium(II) coordination polymers of [Cd(Phac)2(Dabco)(H2O)]n (1) and [Cd(Phac)(4,4′-Bpy)(OAc)]n (2) (Phac = phenylacetate, Dabco = 1,4-diazabicyclo[2.2.2]octane, 4,4′-Bpy = 4,4′-bipyridine, OAc = acetate) have been synthesized by the solvothermal, sonochemical and mechanochemical methods. Single-crystal X-ray diffraction analysis, Fourier-transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRPD), field emission scanning electron microscopy (FE-SEM) and thermal techniques (TG-DTG) were used to study these compounds. In both compounds, phenylacetate is obtained by in situ decarboxylation of phenylmalonic acid. The stability and in vitro antibacterial activity of the compounds were investigated. Metal–ligand bond strength, pillar size, ligand shielding effect, and the nature of network expansion bonds were influential factors in the stability. More stability and the consequent higher lipophilicity of particles were associated with improved antibacterial activity for 1. Nano-grains in the bulk structure of compounds were also identified as a determining factor in antibacterial activity. [ABSTRACT FROM AUTHOR]