The 2D conductive metal–organic frameworks (MOFs) are expected to be an ideal electrocatalyst due to their high utilization of metal atoms. Exploring a new conjugated ligand with extra active metallic center can further boost the structural advantages of conductive MOFs. In this work, hexaiminohexaazatrinaphthalene (HAHATN) is employed as a conjugated ligand to construct bimetallic sited conductive MOFs (M23(M13∙HAHATN)2) with an extra M–N2 moiety. Density functional theory (DFT) calculations demonstrate that the 2D conjugated framework renders M23(M13∙HAHATN)2 a high electric conductivity with narrow bandgap (0.19 eV) for electron transfer and a favorable in‐plane porous structure (2.7 nm) for mass transfer. Moreover, the metal atom at the extra M–N2 moiety has a higher unsaturation degree than that at M–N4 linkage, resulting in a stronger ability to donate electrons for enhancing electroactivity. These characteristics endow the new conductive MOFs with an enhanced electroactivity for hydrogen evolution reaction (HER) electrocatalysis. Among the series of M23(M13∙HAHATN)2 MOF, Ni3(Ni3∙HAHATN)2 nanosheets with the optimal structure exhibit a small overpotential of 115 mV at 10 mA cm−2, low Tafel slope of (45.6 mV dec−1), and promising electrocatalytic stability for HER. This work provides an effective strategy for designing conductive MOFs with a favorable structure for electrocatalysis.

The hydrogen bonding interaction between the amide functional group and water is fundamental to understanding the liquid–liquid heterogeneity in biological systems. Herein, the structure and dynamics of the N,N-dimethyl­formamide (DMF)–water mixtures have been investigated by linear and nonlinear IR spectroscopies, using the hydroxyl stretch and extrinsic probe of thiocyanate as local vibrational reporters. According to vibrational relaxation dynamics measurements, the orientational dynamics of water is not directly tied to those of DMF molecules. Wobbling-in-a-cone analysis demonstrates that the water molecules have varying degrees of angular restriction depending on their composition due to the formation of specific water–DMF networks. Because of the preferential solvation by DMF molecules, the rotational dynamics of the extrinsic probe is slowed significantly, and its rotational time constants are correlated to the change of solution viscosity. The unique structural dynamics observed in the DMF–water mixtures is expected to provide important insights into the underlying mechanism of microscopic heterogeneity in binary mixtures.

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The structure and anion recognition dynamics between calix[4]pyrroles and azide (N 3 − ) anions in the form of its TBA + and Na + salts were investigated in dimethyl sulfoxide solutions by Fourier transform infrared (FTIR) spectroscopy and ultrafast IR spectroscopy. Vibrational energy redistribution of the N 3 − anion in the complex is accelerated through hydrogen bonding interactions with the N−H proton of the receptor. Rotational dynamics of the bound N 3 − is greatly restricted, demonstrating a distinct countercation effect. The detailed binding modes of N 3 − with the receptor were further evaluated by the density functional theoretical (DFT) calculations and nuclear magnetic resonance (NMR) spectroscopy. All of these measurements support the notion that the calix [4]pyrroles are capable of capturing the azide anion in solution. However, the calix[4]pyrroles may not necessarily undergo a conformational change to a conelike geometry when they bind to the azide anion in the solution.

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