Synthesis and Thermochromic Luminescence of Ag(I) Complexes Based on 4,6-Bis(diphenylphosphino)-Pyrimidine

Unusual Coordination Type of the Halogenated Bian Ligands in Silver(I) Complexes

This work presents the synthesis and crystal structures of novel Ag(I) complexes based on 1,2-bis[4-chlorophenyl)imino]acenaphthene (4-Cl-C6H4-bian) and 1,2-bis[4-iodophenyl)imino]acenaphthene (4-I-C6H4-bian). The interaction of AgCF3SO3 with 4-Cl-C6H4-bian led to exclusively tetrahedral complex [Ag(4-Cl-C6H4-bian)2](CF3SO3) (1) in a 90 % yield. In contrast, the same reaction with 4-I-C6H4-bian led to the formation of both tetrahedral complex [Ag(4-I-C6H4-bian)2](CF3SO3) (2) and unexpected binuclear complex [Ag2(μ-4-I-C6H4-bian)2(4-I-C6H4-NH2)2](CF3SO3)2 (3), in which 4-I-C6H4-bian acts as a bridging ligand linking two Ag(I) ions via N- and I-donor atoms. X-ray diffraction analysis revealed an anomalously long Ag-I distance (3.0833(3) Å) in 3, resulting in duality in determining the coordination mode of the Ag(I) ion. This could be a trigonal geometry (AgN3, CN=3) or a strongly distorted trigonal-pyramidal [3+1] coordination (AgN3I, CN=4). To establish the nature of the metal-ligand interactions in complexes 1-3 and determine the coordination number of Ag(I) in complex 3, a comprehensive theoretical study (DFT calculations) was carried out using four molecular descriptors: quantum theory of atoms in molecules (QTAIM), electron localization function (ELF), interacting quantum atoms (IQA) and second-order perturbation theory analysis of the natural bond orbital (NBO).

A Multiple Stimuli-Responsive Ag/P/S Complex Showing Solvochromic and Mechanochromic Photoluminescence

The reaction of CF₃COOAg, 3-bdppmapy (N,N-bis(diphenylphosphanylmethyl)-3-aminopyridine) and HTZ (1,2,4-triazole-3-thiol) in CH₂Cl₂/MeOH resulted in a dinuclear Ag/P/S complex [Ag₂(TZ)₂(3-bdppmapy)₂]·xSol (1·xSol). Crystals of 1·xSol converted to 1·2MeOH in air at room temperature and further to 1 under vacuum upon heating. The solid-state, room-temperature photoluminescent emission of 1·xSol (510 nm) shifted to 494 nm (1·2MeOH) and 486 nm (1). Grinding solids of 1·2MeOH in air resulted in amorphous 1G characterized by solid-state emission at 468 nm, which converted to 1GR with 513 nm emission upon MeOH treatment. Grinding 1GR in air returned 1G, and this interconversion was reproducible over five cycles. The solid-state photoluminescence of 1G changed in response to vapors containing low-molecular weight alcohols but remained unchanged after exposure to other volatile organic compounds (VOCs) or to water vapor. Test papers impregnated with 1G could detect methanol in vapors from aqueous solutions at concentrations above 50%. Complex 1G is, therefore, an example of a stimuli-responsive molecular sensor for the detection of alcohols.

A One-Dimensional Cu(I) Coordination Polymer with Optical Sensing of Oxygen and Temperature

Due to their tight structures, it is usually difficult for one-dimensional (1D) coordination polymers (CPs) to form permanent pores unless 2D and 3D topologies are formed via supramolecular interactions, so studies in the field of oxygen sensing on 1D CPs are rarely reported. Here, we report a 1D Cu(I) cluster-based CP with dual sensing characteristics for temperature and oxygen. Even if the porosity is only 6.6%, the quenching rate of this CP reaches 98.4% with 1 bar O2 at room temperature. Its luminescence intensity exhibits a unique thermal “quenching, then activating” behavior during monotonic variations in temperature.

Trapping of Ag+ into a Perfect Six-Coordinated Environment: Structural Analysis, Quantum Chemical Calculations and Electrochemistry

Self-assembly of (Bu4N)4[β-Mo8O26], AgNO3, and 2-bis[(2,6-diisopropylphenyl)-imino]acenaphthene (dpp-bian) in DMF solution resulted in the (Bu4N)2[β-{Ag(dpp-bian)}2Mo8O26] (1) complex. The complex was characterized by single crystal X-ray diffraction (SCXRD), X-ray powder diffraction (XRPD), diffuse reflectance (DR), infrared spectroscopy (IR), and elemental analysis. Comprehensive SCXRD studies of the crystal structure show the presence of Ag+ in an uncommon coordination environment without a clear preference for Ag-N over Ag-O bonding. Quantum chemical calculations were performed to qualify the nature of the Ag-N/Ag-O interactions and to assign the electronic transitions observed in the UV-Vis absorption spectra. The electrochemical behavior of the complex combines POM and redox ligand signatures. Complex 1 demonstrates catalytic activity in the electrochemical reduction of CO2.

Self-assembly patterns of non-metalloid silver thiolates: structural, HR-ESI-MS and stability studies

Screening of AgNO₃/AgS^tBu solutions in DMF, DMSO and NMP resulted in the isolation of three novel nanosized silver/thiolate complexes with a torus-like {Ag₂₀(S^tBu)₁₀} core. The structures of [NO₃@Ag₂₀(S^tBu)₁₀(NO₃)₉(DMF)₆] (1) and [NO₃@Ag₂₀(^tBuS)₁₀(NO₃)₈(NMP)₈][NO₃@Ag₁₉(^tBuS)₁₀(NO₃)₈(NMP)₆]₂(NO₃) (2) were studied by single crystal X-ray diffraction (SCXRD). The self-assembly process leading to 1 can be switched to a different outcome using Br^-, resulting in [Br@Ag₁₆(S^tBu)₈(NO₃)₅(DMF)₃](NO₃)₂ (3), which is the one of the few genuine host-guest complexes in the silver/thiolate systems. Solutions of the individual complexes in CH₃CN were studied by HR-ESI-MS techniques, which revealed a dynamic behavior for each complex, driven by a redistribution of the {AgNO₃} units. This dynamics results in the appearance of both cationic and anionic species, based on unchanged silver-thiolate cores. Daylight causes degradation of 3 with the formation of a composite material based on defective orthorhombic Ag₂S with a porous morphology, as observed using the SEM technique. The electrocatalytic HER activity of such a material was studied.

Editorial for Special Issue “Functional Coordination Polymers and Metal–Organic Frameworks”

Metal–Organic Frameworks (MOFs) and Coordination Polymers (CPs) are at the forefront of contemporary coordination chemistry research, as witnessed by the impressive (and ever-growing) number of publications appearing in the literature on this topic in the last 20 years (Figure 1), reaching almost 4000 papers in 2020 [...]