Fast and reversible solvent-vapor-induced 1D to 2D transformation in emissive Ag(I)-organic networks.

We report here an unprecedentedly fast and reversible transformation between 1D and 2D MOFs/CPs induced through organic solvent vapours. The transformations occur at room temperature in just 15-20 min, accompanied by a significant change in the observed phosphorescence. These findings provide a new insight into the design of luminescent networks with stimuli-switchable dimensionality.

Synthesis, Structure, and Magnetic and Biological Properties of Copper(II) Complexes with 1,3,4-Thiadiazole Derivatives.

New coordination compounds of copper(II) with 2,5-bis(ethylthio)-1,3,4-thiadiazole (L1) and 2,5-bis(pyridylmethylthio)-1,3,4-thiadiazole (L2) with compositions Cu(L1)2Br2, Cu(L1)(C2N3)2, Cu(L2)Cl2, and Cu(L2)Br2 were prepared. The complexes were identified and studied by CHN analysis, infrared (IR) spectroscopy, powder X-Ray diffraction (XRD), and static magnetic susceptibility. The crystal structures of Cu(II) complexes with L1 were determined. The structures of the coordination core of complexes Cu(L2)Cl2 and Cu(L2)Br2 were determined by Extended X-ray absorption fine structure (EXAFS) spectroscopy. Magnetization measurements have revealed various magnetic states in the studied complexes, ranging from an almost ideal paramagnet in Cu(L1)2Br2 to alternating-exchange antiferromagnetic chains in Cu(L1)(C2N3)2, where double dicyanamide bridges provide an unusually strong exchange interaction (J1/kB ≈ -23.5 K; J2/kB ≈ -20.2 K) between Cu(II) ions. The cytotoxic activity of copper(II) complexes with L2 was estimated on the human cell lines of breast adenocarcinoma (MCF-7) and hepatocellular carcinoma (HepG2).

Strong Magnetically-Responsive Circularly Polarized Phosphorescence and X-Ray Scintillation in Ultrarobust Mn(II)-Organic Helical Chains.

Over recent years, Mn(II)-organic materials showing circularly polarized luminescence (CPL) have attracted great interest because of their eco-friendliness, cheapness, and room temperature phosphorescence. Using the helicity design strategy, herein, chiral Mn(II)-organic helical polymers are constructed featuring long-lived circularly polarized phosphorescence with exceptionally high glum and ΦPL magnitudes of 0.021% and 89%, respectively, while remaining ultrarobust toward humidity, temperature, and X-rays. Equally important, it is disclosed for the first time that the magnetic field has a remarkably high negative effect on CPL for Mn(II) materials, suppressing the CPL signal by 4.2-times at B ⃗ $\vec{B}$  = 1.6 T. Using the designed materials, UV-pumped CPL light-emitting diodes are fabricated, demonstrating enhanced optical selectivity under right- and left-handed polarization conditions. On top of all this, the reported materials display bright triboluminescence and excellent X-ray scintillation activity with a perfectly linear X-ray dose rate response up to 174 µGyair  s-1 . Overall, these observations significantly contribute to the CPL phenomenon for multi-spin compounds and promote the design of highly efficient and stable Mn(II)-based CPL emitters.

Recent progress in dichalcophosphate coinage metal clusters and superatoms.

Atomically precise clusters of group 11 metals (Cu, Ag, and Au) attract considerable attention owing to their remarkable structure and fascinating properties. One of the unique subclasses of these clusters is based on dichalcophosphate ligands of [(RO)2PE2]- type (E = S or Se, and R = alkyl). These ligands successfully stabilise the most diverse Cu, Ag, and Au clusters and superatoms, spanning from simple ones to amazing assemblies featuring unusual structural and bonding patterns. It is noteworthy that such complicated clusters are assembled directly from cheap and simple reagents, metal(I) salts and dichalcophosphate anions. This reaction, when performed in the presence of a hydride or other anion sources, or foreign metal ions, results in hydrido- or anion-templated homo- or heteronuclear structures. In this feature article, we survey the recent advances in this exciting field, highlighting the powerful synthetic capabilities of the system "a metal(I) salt - [(RO)2PX2]- ligands - a templating anion or borohydride" as an inexhaustible platform for the creation of new atomically precise clusters, superatoms, and nanoalloys.

TADF and X-ray Radioluminescence of New Cu(I) Halide Complexes: Different Halide Effects on These Processes.

A series of complexes [Cu2X2(Pic3PO)2] (X = Cl, Br, I) based on tris(pyridin-2-ylmethyl)phosphine oxide (Pic3PO) has been synthesized. At 298 K, these compounds exhibit thermally activated delayed fluorescence (TADF) of 1(M+X)LCT type with λmax varying from 485 to 545 nm, and quantum efficiency up to 54%. In the TADF process, the halide effect appears as the emission intensification and bathochromic shift of λmax in the following order X = I < Br < Cl. Upon X-ray irradiation, the title compounds emit radioluminescence, the emission bands of which have the same shape as those at TADF, thereby meaning a similar radiative excited state. By contrast to TADF, the halide effect in the radioluminescence is reversed: its intensity grows in the order X = Cl < Br < I, since heavier atoms absorb X-rays more efficiently. These findings essentially contribute to our knowledge about the halide effect in the photo- and radioluminescent Cu(I) halide emitters.

A family of CuI-based 1D polymers showing colorful short-lived TADF and phosphorescence induced by photo- and X-ray irradiation.

Exploiting 2-(alkylsulfonyl)pyridines as 1,3-N,S-ligands, herein we have constructed 1D CuI-based coordination polymers (CPs) bearing unprecedented (CuI)n chains and possessing remarkable photophysical properties. At room temperature, these CPs show efficient TADF, phosphorescence or dual emission in the deep-blue to red range with outstandingly short decay times of 0.4-2.0 µs and good quantum performance. Owing to great structural diversity, the CPs demonstrate a variety of emissive mechanisms, spanning from TADF of 1(M + X)LCT type to 3CC and 3(M + X)LCT phosphorescence. Moreover, the designed compounds emit strong X-ray radioluminescence with the quantum efficiency of up to an impressive 55% relative to all-inorganic BGO scintillators. The presented findings push the boundaries in designing TADF and triplet emitters with very short decay times.

A new subclass of copper(I) hybrid emitters showing TADF with near-unity quantum yields and a strong solvatochromic effect.

We introduce here a new subclass of copper(I) hybrid emitters simultaneously containing [CuxIy]z- anions and Cu+ cations, separated in space by a Janus head ligand. When UV-irradiated at 298 K, these unique "Two-In-One" hybrids exhibit a short-lived green TADF with near-unity quantum yield and a strong solvatochromic effect. Moreover, they manifest a strong radioluminescence upon X-ray irradiation. These findings open up new possibilities for the design of highly performing TADF materials.

Halogen Bonding Channels for Magnetic Exchange in Cu(II) Complexes with 2,5-Di(methylthio)-1,3,4-thiadiazole.

Copper(II) complexes with 2,5-bis(methylthio)-1,3,4-thiadiazole (tda) formulated as [Cu(tda)n X2 ] (n=2, X=Cl- , Br- , C2 N3 - ; n= 1, X=C2 N3 - ) have been isolated and fully characterized. The crystal structures of all compounds have been determined using single-crystal X-ray diffraction (SCXRD). A study of the magnetic susceptibility in the range 1.77-300 K has shown that magnetic properties of the [Cu(tda)2 Cl2 ] and [Cu(tda)2 Br2 ] complexes match those of 1D chains of antiferromagnetically-coupled Cu2+ ions. The intrachain interaction J in [Cu(tda)2 Cl2 ] turns out to be ∼1.2 times weaker than in its bromide analogue. In its turn, [Cu(tda)2 (C2 N3 )2 ] exhibits J being an order of magnitude smaller and of the opposite ferromagnetic sign. Halogen bonding (HB) between adjacent complexes is much stronger than the H-bonds or π-π interactions between tda ligands according to the DFT calculations.

Tris(2-Pyridyl)Arsine as a New Platform for Design of Luminescent Cu(I) and Ag(I) Complexes.

The coordination behavior of tris(2-pyridyl)arsine (Py3As) has been studied for the first time on the example of the reactions with CuI, CuBr and AgClO4. When treated with CuI in CH2Cl2 medium, Py3As unexpectedly affords the scorpionate complex [Cu(Py3As)I]∙CH2Cl2 only, while this reaction in MeCN selectively leads to the dimer [Cu2(Py3As)2I2]. At the same time, the interaction of CuBr with Py3As exclusively gives the dimer [Cu2(Py3As)2Br2]. It is interesting to note that the scorpionate [Cu(Py3As)I]∙CH2Cl2, upon fuming with a MeCN vapor (r.t., 1 h), undergoes quantitative dimerization into the dimer [Cu2(Py3As)2I2]. The reaction of Py3As with AgClO4 produces complex [Ag@Ag4(Py3As)4](CIO4)5 featuring a Ag-centered Ag4 tetrahedral kernel. At ambient temperature, the obtained Cu(I) complexes exhibit an unusually short-lived photoluminescence, which can be tentatively assigned to the thermally activated delayed fluorescence of (M + X) LCT type (M = Cu, L = Py3As; X = halogen). For the title Ag(I) complexes, QTAIM calculations reveal the pronounced argentophilic interactions for all short Ag∙∙∙Ag contacts (3.209-3.313 Å).

Trigonal Planar Au@Ag3 Clusters Showing Exceptionally Fast and Efficient Phosphorescence in Violet to Deep-Blue Region.

We report here a series of original ligand-supported trigonal planar Au@Ag3 clusters exhibiting bright solid-state phosphorescence in violet to deep-blue range (λmax =410-442 nm) with remarkably short decay times (0.36-1.36 µs) and up to 96 % emission quantum yield at 298 K.

Controllable Synthesis and Luminescence Behavior of Tetrahedral Au@Cu4 and Au@Ag4 Clusters Supported by tris(2-Pyridyl)phosphine.

We report herein a family of polynuclear complexes, [Au@Ag4(Py3P)4]X5 and [Au@Cu4(Py3P)4]X5 [X = NO3, ClO4, OTf, BF4, SbF6], containing unprecedented Au-centered Ag4 and Cu4 tetrahedral cores supported by tris(2-pyridyl)phosphine (Py3P) ligands. The [Au@Ag4]5+ clusters are synthesized via controlled substitution of the central Ag(I) ion in all-silver [Ag@Ag4]5+ precursors by the reaction with Au(tht)Cl, while the [Au@Cu4]5+ cluster is assembled through the treatment of a pre-organized [Au(Py3P)4]+ metallo-ligand with 4 equiv of a Cu(I) source. The structure of the Au@M4 clusters has been experimentally and theoretically investigated to reveal very weak intermolecular Au-M metallophilic interactions. At ambient temperature, the designed compounds emit a modest turquoise-to-yellow luminescence with microsecond lifetimes. Based on the temperature-dependent photophysical experiments and DFT/TD-DFT computations, the emission observed has been assigned to an MLCT or LLCT type depending on composition of the cluster core.

New Approach toward Dual-Emissive Organic-Inorganic Hybrids by Integrating Mn(II) and Cu(I) Emission Centers in Ionic Crystals.

Inorganic-organic hybrid luminescent materials have received great attention for their potential applications in a wide range of clean/renewable energy-related areas, including photovoltaics and solid-state lighting. Herein, we present a unique and general "Mn + Cu" approach by blending two earth-abundant luminogenic metals, manganese and copper, within a single ionic structure to construct a remarkable family of low-cost and multifunctional hybrid materials featuring dual emission, as well as triboluminescence and second-harmonic generation response. The novel hybrid materials are made of diphosphine dioxide-chelated [Mn(O∧O)3]2+ cations and various anionic [CuxIy](y-x)- clusters, ensuring manifestation of dual phosphorescence streamed from octahedral Mn2+ ions (605-648 nm) and iodocuprate anions (480-728 nm). Noteworthily, the relative ratio of the emission bands, and hence a resulting emission chromaticity, can be tuned in a wide range through modification of cluster [CuxIy](y-x)- modules. The structural diversity, enhanced robustness, and up to 100% luminescence quantum yield make the designed materials promising phosphors for lighting and sensing applications.

Pyridylarsine-based Cu(I) complexes showing TADF mixed with fast phosphorescence: a speeding-up emission rate using arsine ligands.

Can arsine ligands be preferred over similar phosphines to design Cu(I)-based TADF materials? The present study reveals that arsines can indeed be superior to reach shorter decay times of Cu(I) emitters. This has been exemplified on a series of bis(2-pyridyl)phenylarsine-based complexes [Cu2(Py2AsPh)2X2] (X = Cl, Br, and I), the emission decay times of which are significantly shorter (2-9 µs at 300 K) than those of their phosphine analogs [Cu2(Py2PPh)2X2] (5-33 µs). This effect is caused by two factors: (i) large ΔE(S1-T1) gaps of the arsine complexes (1100-1345 cm-1), thereby phosphorescence is admixed with TADF at 300 K, thus reducing the total emission decay time compared to the TADF-only process by 5-28%; (ii) higher SOC strength of arsenic (ζl = 1202 cm-1) against phosphorus (ζl = 230 cm-1) makes the kr(T1 → S0) rate of the Cu(I)-arsine complexes by 1.3 to 4.2 times faster than that of their phosphine analogs. It is also noteworthy that the TADF/phosphorescence ratio for [Cu2(Py2AsPh)2X2] at 300 K is halogen-regulated and varies in the order: Cl (1 : 1) < Br (3 : 1) ≈ I (3.5 : 1). These findings provide a new insight into the future design of dual-mode (TADF + phosphorescence) emissive materials with reduced lifetimes.

Coordination-induced emission enhancement in copper(I) iodide coordination polymers supported by 2-(alkylsulfanyl)pyrimidines.

First examples of copper(i) complexes with 2-(alkylsulfanyl)pyrimidine ligands have been synthesized. Reactions of copper(i) iodide with 2-(methylsulfanyl)pyrimidine (L1) in various metal-to-ligand molar ratios in MeCN afford a ladder-type coordination polymer [Cu2L1I2]n with polymeric chains built from double-stranded (Cu2I2)n ribbons supported on both sides by µ2-N,S-L1 molecules. Although the second ligand, 2-(ethylsulfanyl)pyrimidine (L2), differs from L1 only by a methylene group, its reactions with copper(i) iodide in MeCN yield not only a congenerous coordination polymer, [Cu2L2I2]n, but also [CuL2I]n, in which a similar (Cu2I2)n ribbon is decorated by N-monodentate L2 molecules. Absorption spectra of all compounds represent an interplay of metal + iodine-to-ligand charge transfer (XMLCT) and ligand-centered (LC) and cluster-centered (CC) transitions, while the emission occurs from the excited states of XMLCT nature. The luminescence of [Cu2L1I2]n and [Cu2L2I2]n is blue-shifted and greatly enhanced in comparison with that of [CuL2I]n (quantum yields: 89% and 68% for [Cu2L1I2]n and [Cu2L2I2]nvs. 23% for [CuL2I]n at 77 K), which can be associated with a more rigid µ2-N,S coordination of 2-(alkylsulfanyl)pyrimidine ligands in [Cu2L1I2]n and [Cu2L2I2]n leading to a less distorted T1 state.

Silver(I)-Organic Frameworks Showing Remarkable Thermo-, Solvato- And Vapochromic Phosphorescence As Well As Reversible Solvent-Driven 3D-to-0D Transformations.

A series of isoreticular Ag(I) luminescent metal-organic frameworks (LMOFs), {[Ag2L2(CH3CN)2](X)2}n (X = ClO4, OTf, and BF4), has been designed, exploiting diphenyl(2-pyrazyl)phosphine (L) as a multidentate linker. At ambient temperature, these compounds emit a bright long-lived phosphorescence (λem = 545-555 nm) with a quantum efficiency as high as 22%, which is the highest value for phosphorescent Ag-LMOFs. The prepared LMOFs also exhibit pronounced thermochromic luminescence, reversibly changing their emission color in the 300-77 K range. These LMOFs also demonstrate prominent solvato- and vapochromic luminescence, which manifest as a reversible change in the emission properties during the removal and recovery of the coordinated and guest MeCN molecules, respectively. Moreover, we have discovered a reversible solvent-driven 3D-to-0D transformation of the framework {[Ag2L2(CH3CN)2](ClO4)2}n into a brightly emissive complex [Ag4L4(ClO4)4]. To the best of our knowledge, the compounds obtained are the first Ag-LMOFs that exhibit thermo-, solvato-, and vapochromic luminescence.

Selenium Nanocomposites in Natural Matrices as Potato Recovery Agent.

The paper presents a study of the effect of chemically synthesized selenium nanocomposites (Se NCs) in natural polymer matrices arabinogalactan (AG) and starch (ST) on the viability of the potato ring rot pathogen Clavibacter sepedonicus (Cms), potato plants in vitro, and the soil bacterium Rhodococcus erythropolis. It was found that the studied Se NCs have an antibacterial effect against the phytopathogenic Cms, reducing its growth rate and ability to form biofilms. It was revealed that Se NC based on AG (Se/AG NC) stimulated the growth and development of potato plants in vitro as well as their root formation. At the same time, Se did not accumulate in potato tissues after the treatment of plants with Se NCs. The safety of the Se NCs was also confirmed by the absence of a negative effect on the growth and biofilm formation of the soil bacterium R. erythropolis. The obtained results indicate that Se NCs are promising environmentally safe agents for the protection and recovery of cultivated plants from phytopathogenic bacteria.

Beyond Classical Coordination Chemistry: The First Case of a Triply Bridging Phosphine Ligand.

The first example of a triply bridging (µ3 -P) phosphine ligand has been discovered in the crown-shaped [Cu3 (µ2 -Hal)3 L] (Hal=Cl, Br, or I) complexes supported by tris[2-(2-pyridyl)ethyl]phosphine (L). Theoretical analysis completely confirms the observed µ3 -P-bridging pattern, revealing the interaction of the same lone pair of phosphorus with three valence 4s-orbitals of Cu atoms. The presented complexes exhibit outstanding blue phosphorescence (λem =442-465 nm) with the quantum efficiency reaching 100 %. The complex [Cu3 (µ2 -I)3 L] also exhibits remarkable thermo- and mechanochromic luminescence resulting in a sharp change in the emission colour upon external stimuli. These findings essentially contribute to coordination chemistry of the pnictine ligands.

Dicopper(I) Paddle-Wheel Complexes with Thermally Activated Delayed Fluorescence Adjusted by Ancillary Ligands.

A suite of paddle-wheel shaped [Cu2(PymPPh2)3(Lan)n](PF6)2 complexes showing efficient thermally activated delayed fluorescence (TADF) has been synthesized. In these complexes, Cu(I) ions are P,N-bridged by three diphenyl(2-pyrimidyl)phosphine (PymPPh2, L) ligands in a "head-to-tail" fashion, and one or both metals are also capped by the ancillary ligand (Lan = MeOH, Me2CO, MeCN, PhCN). At ambient temperature, the solid complexes emit TADF with the quantum yield of up to 85% and the lifetimes of from 9.6 to 27 µs. The ancillary ligands, whose orbitals negligibly contribute to the radiative 1(M + L + Lan)LCT state, remarkably adjust emission energies and ΔE(S1-T1) energy splitting magnitudes of the emitters obtained. Thus, depending on structure and/or number of the Lan molecules, the emission maxima vary from 500 to 563 nm, and the ΔE(S1-T1) gaps range 550-1100 cm-1. Such tunable TADF characteristics coupled with the excellent solubility and air-stability make the complexes presented to be promising TADF materials.

New Cu(i) halide complexes showing TADF combined with room temperature phosphorescence: the balance tuned by halogens.

A series of Cu(i) halide complexes derived from tris(2-pyridyl)phosphine (Py3P), [Cu2(Py3P)2X2] (X = Cl, Br, I), have been synthesized by a straightforward reaction in solution or through a mechanochemical route. At room temperature, the solid complexes exhibit bright dual-mode photoluminescence (λmax = 520-550 nm, τ = 14.5-20.0 µs, and ΦPL ≈ 53%), expressed by thermally activated delayed fluorescence (TADF) combined with phosphorescence (PH), originating from 1(M + X)LCT and 3(M + X)LCT excited states, respectively. Remarkably, the balance of these radiative processes at 300 K is regulated by halogen atom nature, switching from TADF-assisted phosphorescence to PH-admixed TADF. The emission of [Cu2(Py3P)2Cl2] at 300 K is largely contributed by PH (73%) admixed with the TADF fraction (27%) and [Cu2(Py3P)2Br2] also emits mainly PH (65%) admixed with the larger TADF fraction (35%). Meanwhile, for [Cu2(Py3P)2I2], the TADF channel becomes dominating (61%) and PH contribution drops to 39%. The photophysical study corroborated by (TD)DFT computations has revealed that this effect arises mainly from the narrowing of the ΔE(S1 - T1) gap of the [Cu2(Py3P)2X2] complexes in the order Cl (1500 cm-1) > Br (1250 cm-1) > I (1000 cm-1) which facilitates the TADF pathway and suppresses PH in the same order.

Luminescence of the Mn2+ ion in non-Oh and Td coordination environments: the missing case of square pyramid.

The first observation of luminescence for Mn(ii) complexes with a square-pyramidal geometry (C4v) of the metal is reported. The complexes of such type, namely [Mn(L)2Hal]X, where L is an O,O'-chelating ligand Me2N-CH(Ph2P[double bond, length as m-dash]O)2, Hal = Cl or Br, and X = Br, I or [MnCl4], show at ambient temperature red photoluminescence (λ≈ 620 nm) with millisecond lifetimes (3.8-7.6 ms). This emission, stemming from spin-forbidden 4E(G) →6A1(S) transitions in square-pyramidally coordinated Mn2+, is found to be responsive to temperature. Upon cooling the complexes from 300 to 77 K, the red-shift of the emission band by ≈20 nm takes place, which is accompanied by the increase of its integral intensity and lifetime. The peculiarities of the discovered Mn2+(C4v) luminescence are discussed against the classical luminescence that occurs in octahedral (Oh) and tetrahedral (Td) surroundings.