The ordered dimethylammonium cations [H2N(CH3)2](+) and helical water spirals as guest species make a super water stable europium-organic framework possess a proton conductivity of over 10(-3) S cm(-1) at 68% relative humidity. A fluorescent probe for Fe(3+) and Cu(2+) ions via a different mechanism has also been realized.

A crystalline coordination polymer (CP) photocatalyst (Cu-RSH) which combines redox-active copper centers with photoactive rhodamine-derived ligands remains stable in acid and basic solutions from pH 2 to 14, and efficiently catalyzes dihydrogen evolution at a maximum rate of 7.88 mmol g(-1)  h(-1) in the absence of a mediator and a co-catalyst. Cyclic voltammetry, control experiments, and DFT calculations established that copper nodes with open coordination sites and favorable redox potentials, aided by spatially ordered stacking of rhodamine-based linkers, account for the high catalytic performance of Cu-RSH. Emission quenching, time-resolved fluorescence decay, and transient photocurrent experiments disclosed the charge separation and transfer process in the catalytic system. The present study demonstrates the potential of crystalline copper CPs for the practical utilization of light.

Ac rystalline coordination polymer (CP) photocatalyst (Cu-RSH) whichc ombines redox-active copper centers with photoactive rhodamine-derived ligands remains stable in acid and basic solutions from pH 2t o1 4, and efficiently catalyzes dihydrogen evolution at am aximum rate of 7.88 mmol g À1 h À1 in the absence of am ediator and ac ocatalyst. Cyclic voltammetry,c ontrol experiments,a nd DFT calculations established that copper nodes with open coordination sites and favorable redoxp otentials,a ided by spatially ordered stacking of rhodamine-based linkers,a ccount for the high catalytic performance of Cu-RSH. Emission quenching, time-resolved fluorescence decay, and transient photocurrent experiments disclosed the charge separation and transfer process in the catalytic system. The present study demonstrates the potential of crystalline copper CPs for the practical utilization of light.Sunlight-drivensplittingofwater into hydrogen is one of the most promising scenarios for sustainable energy consumption. Thedevelopment of highly efficient, inexpensive noblemetal-free photocatalysts is ap rerequisite,b ut faces many difficult challenges.C oordination polymers (CPs) that combine functional organic ligands with metal centers/clusters (secondary building units,S BUs) have become promising candidates for photoharvesting and the photocatalytic splitting of water. [1][2][3][4] Thes o-far reported CPs for the hydrogen evolution reaction (HER) rely primarily on alimited number of inert Zr-, Al-, Ti-, and Cr-based SBUsa saresult of their stability under harsh catalytic conditions.[2] Moreover,t hey primarily act as supports to host known catalysts that participate in the catalytic reaction, with noble metal Pt particles representing the majority of these catalysts. [2, 3] Developing completely Pt-free and stable CP photocatalysts using redox-active metals,s uch as Fe,C o, Ni, and Cu in combination with photoactive organic ligands would present viable alternatives for transforming sunlight into chemical energy. [1,4]

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