| Summary: | Six new three-dimensional metal–organic frameworks based on early lanthanide(III) cations and <i>trans</i>-1,4-cyclohexanedicarboxylic acid (H<sub>2</sub>chdc) were obtained. Their crystal structures were determined by single-crystal X-ray diffraction analysis. The structure of [La<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>(chdc)<sub>3</sub>]·2DMF·H<sub>2</sub>O (<b>1</b>; DMF = N,N-dimethylformamide) contains one-dimensional infinite La(III)-carboxylate chains interconnected by cyclohexane moieties to form a highly porous polymeric lattice with 30% solvent accessible volume. Compounds [Ln<sub>2</sub>(phen)<sub>2</sub>(chdc)<sub>3</sub>]·0.75DMF (<b>2<sub>Ln</sub></b>; Ln<sup>3+</sup> = Ce<sup>3+</sup>, Pr<sup>3+</sup>, Nd<sup>3+</sup> and Sm<sup>3+</sup>; phen = 1,10-phenanthroline) are based on binuclear carboxylate building blocks, which are decorated by chelate phenanthroline ligands and interconnected by cyclohexane moieties to form more dense isostructural coordination frameworks with primitive cubic <b><i>pcu</i></b> topology. Compound [Nd<sub>2</sub>(phen)<sub>2</sub>(chdc)<sub>3</sub>]·2DMF·0.67H<sub>2</sub>O (<b>3</b>) is based on secondary building units similar to <b>2<sub>Ln</sub></b> and contains a coordination lattice isomeric to <b>2<sub>Ln</sub></b> with a rare hexagonal helical <b><i>snz</i></b> topology. Thermal stability and luminescent properties were investigated. For <b>2<sub>Sm</sub></b>, a strong and nonmonotonous dependence of the luminescence color on the variation of excitation wavelength was revealed, changing its emission from pinkish red at λ<sub>ex</sub> = 340 nm to white at λ<sub>ex</sub> = 400 nm, and then to yellow at lower excitation energies. Such nonlinear behavior was rationalized in terms of the contribution of several different luminescence mechanisms. Thus, <b>2<sub>Sm</sub></b> is a rather rare example of a highly tunable monometallic lanthanide-based luminophore with possible applications in light-emitting devices and optical data processing.
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