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In this study, we used the facile solvent evaporation method to achieve the inorganic–organic hybrid crystals of [triethylpropylammonium][PbI3], which have been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and differential scanning calorimetry as well as single-crystal X-ray structure analysis. The hybrid solid crystallizes in the monoclinic space group P21/cat room temperature and is composed of one-dimensional [PbI3]∞chains, where the neighboring PbI6coordination octahedra connect together via the face-sharing mode and the organic cations fall in the spaces between [PbI3]∞chains. The hybrid exhibits a dielectric phase transition with a critical temperature of ca. 432 K, dielectric relaxation at frequencies below 107Hz, and single-ion conducting behavior, the conductivity of which increases rapidly from 9.43 × 10–10S cm–1at 383 K to 4.47 × 10–5S cm–1at 473 K. The variable-temperature single-crystal and powder X-ray diffraction analyses revealed that the dielectric phase transition is related to the disorder-to-order transformation of cations in the lattice. The electric modulus and impedance spectral analyses further disclosed that the dielectric relaxation arises from the ionic displacement polarization and molecular dipole orientation of cations. The single-ion conductance is due to the migration of cations that fall in the spaces of rigid inorganic [PbI3]∞chains. The phase transition gives rise to this hybrid showing switchable ion-conducting nature around the critical temperature of the phase transition. Besides the fascinating functionalities mentioned above, the hybrid also exhibits a thermochromic luminescence feature originating from the electron transition between the valence and conduction bands of the inorganic [PbI3]∞chain.

A Zn-based metal-organic framework (MOF)/porous coordination polymer (PCP), (EMIM)[Zn(SIP)] (1) (SIP3–= 5-sulfoisophthalate, EMIM+= 1-ethyl-3-methylimidazolium), was synthesized using the ionothermal reaction. The Zn2+ion adopts distorted square pyramid coordination geometry with five oxygen atoms from three carboxylates and one sulfo group. One of two carboxylates in SIP3–serves as a μ2-bridge ligand to link two Zn2+ions and form the dinuclear SBU, and such SBUs are connected by SIP3–ligands to build the three-dimensional framework with rutile (rtl) topology. The cations from the ion-liquid fill the channels. This MOF/PCP shows two-step dielectric anomalies together with two-step dielectric relaxations; the variable-temperature single-crystal structure analyses disclosed the dielectric anomaly occurring at ca. 280 K is caused by an isostructural phase transition. Another dielectric anomaly is related to the dynamic disorder of the cations in the channels. Electric modulus, conductance, and variable-temperature solid-state 13C CP/MAS NMR spectra analyses revealed that two-step dielectric relaxations result from the dynamic motion of the cations as well as the direct-current conduction and electrode effect, respectively.

Two new Pb2+-based coordination polymers (CPs), [Pb2(HBTC)2(DMF)] (1) and [Pb(HPTC)] (2), have been synthesized under solvothermal condition; herein, H3BTC and H3PTC represent 1,3,5-benzenetricarboxylic acid and 2,4,6-pyridine tricarboxylic acid, respectively. Both 1and 2were characterized by microanalysis, infrared spectra (IR), thermal gravimetric analyses (TGA), and powder X-ray diffraction (PXRD) techniques. Single-crystal structural analysis indicates that 1and 2show different coordination sphere around Pb2+ions and distinct coordination frameworks. The I1O2type three-dimensional (3D) nonporous metal–organic framework forms in 1, where the Pb2+ion shows holo-directed coordination geometry, while the I0O2type two-dimensional (2D) coordination polymeric layered structure forms in 2, where Pb2+ion shows a hemidirected coordination sphere and the 6s2lone electron pair in Pb2+ion is stereochemically active. The two CPs emit intense and long-lasting greenish phosphorescence in air at room temperature, with absolute quantum yields of 1.2% for 1and 4.7% for 2and decay lifetimes of 0.73 ms for 1and 1.52 ms for 2.