Sulfide-Induced Dimerization Versus Demetallation of Tricopper(I) Clusters Protected by Tris-Thiolato Metalloligands.

Here, we report the reactivity of copper(I) clusters toward sulfide ions; these sulfide copper(I) clusters have attracted much attention due to their relevance to biologically active centers and their fascinating structural and photophysical properties. Treatment of the CuI 3RhIII 2 pentanuclear complex, [Cu3{Rh(aet)3}2]3+ (aet=2-aminoethanethiolate), in which a {CuI 3}3+ cluster moiety is bound by two fac-[Rh(aet)3] metalloligands, with NaSH in water produced the CuI 6RhIII 4 decanuclear complex, [Cu6S{Rh(aet)3}4]4+, accompanied by the dimerization of [Cu3{Rh(aet)3}2]3+ and the incorporation of a sulfide ion at the center. While similar treatment using the analogous CuI 3IrIII 2 complex with fac-[Ir(aet)3] metalloligands, [Cu3{Ir(aet)3}2]3+, produced the isostructural CuI 6IrIII 4 decanuclear complex, [Cu6S{Ir(aet)3}4]4+, the use of the CuI 3RhIII 2 complex with fac-[Rh(apt)3] metalloligands, [Cu3{Rh(apt)3}2]3+ (apt=3-aminopropanethiolate), resulted in the removal of one of the three CuI atoms from {CuI 3}3+ to afford the CuI 2RhIII 2 tetranuclear complex, [Cu2{Rh(apt)3}2]2+.

Polymorphism and Its Influence on Catalytic Activities of Lanthanide-Glutamate-Oxalate Coordination Polymers.

To study the relationship between polymorphism and catalytic activities of lanthanide coordination polymers in the cycloaddition reactions of CO2 with epoxides, the monoclinic and triclinic polymorphs of [LnIII(NH3-Glu)(ox)]·2H2O, where LnIII = LaIII (I), PrIII (II), NdIII (III), SmIII (IV), EuIII (V), GdIII (VI), TbIII (VII), and DyIII (VIII), NH3-Glu- = NH3+ containing glutamate, and ox2- = oxalate, were synthesized and characterized. Factors determining polymorphic preference, the discrepancy between the two polymorphic framework structures, potential acidic and basic sites, thermal and chemical stabilities, active surface areas, void volumes, CO2 sorption/desorption isotherms, and temperature-programmed desorption of NH3 and CO2 are comparatively presented. Based on the cycloaddition of CO2 with epichlorohydrin in the presence of tetrabutylammonium bromide under solvent-free conditions and ambient pressure, catalytic activities of the two polymorphs were evaluated, and the relationship between polymorphism and catalytic performances has been established. Better performances of the monoclinic catalysts have been revealed and rationalized. In addition, the scope of monosubstituted epoxides was experimented and the outstanding performance of the monoclinic catalyst in the cycloaddition reaction of CO2 with allyl glycidyl ether under ambient pressure has been disclosed.

Postsynthetic Installation of Lanthanide Cubane Clusters in a 3D Hydrogen-Bonded Framework of IrIII4ZnII4 Multicarboxylates.

Immersing single crystals of (Δ)4-K6[Ir4Zn4O(l-cysteinate)12]·nH2O (K6[1Ir]·nH2O) bearing 12 free carboxylate groups, which was newly prepared from Δ-H3[Ir(l-cysteinate)3], ZnBr2, ZnO, and KOH, in an aqueous solution of lanthanide(III) acetate produced Ln2[1Ir]·nH2O (2Ln; Ln = LaIII, CeIII, PrIII, and NdIII) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1Ir]·nH2O (3Ln; Ln = SmIII, EuIII, GdIII, TbIII, DyIII, ErIII, HoIII, TmIII, YbIII, and LuIII) in a single-crystal-to-single-crystal transformation manner. X-ray crystallography showed that the KI ions in K6[1Ir]·nH2O are completely exchanged by the LnIII ions in 2Ln and 3Ln, retaining the 3D hydrogen-bonded framework that consists of the IrIII4ZnII4 complex anions of [1Ir]6-. While 2Ln contained the LnIII ions as isolated aqua species, the LnIII ions in 3Ln existed as cationic cubane clusters of [Ln4(OH)4(OAc)3(H2O)7]5+; these were linked by [1Ir]6- anions through carboxylate groups in a 3D polymeric structure. 3Ln showed magnetic and photoluminescence properties that are characteristically observed for discrete LnIII species in the solid state.

Photo-Controlled Reversible Uptake and Release of a Modified Sulfamethoxazole Antibiotic Drug from a Pillar[5]arene Cross-Linked Gelatin Hydrogel.

Pillararene cross-linked gelatin hydrogels were designed and synthesized to control the uptake and release of antibiotics using light. A suite of characterization techniques ranging from spectroscopy (FT-IR, 1H and 13C NMR, and MAS NMR), X-ray crystallographic analysis, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) was employed to investigate the physicochemical properties of hydrogels. The azobenzene-modified sulfamethoxazole (Azo-SMX) antibiotic was noncovalently incorporated into the hydrogel via supramolecular host-guest interactions to afford the A-hydrogel. While in its ground state, the Azo-SMX guest has a trans configuration structure and forms a thermodynamically stable inclusion complex with the pillar[5]arene motif in the hydrogel matrix. When the A-hydrogel was exposed to 365 nm UV light, Azo-SMX underwent a photoisomerization reaction. This changed the structure of Azo-SMX from trans to cis, and the material was released into the environment. The Azo-SMX released from the hydrogel was effective against both Gram-positive and Gram-negative bacteria. Importantly, the A-hydrogel exhibited a striking difference in antibacterial activity when applied to bacterial colonies in the presence and absence of UV light, highlighting the switchable antibacterial activity of A-hydrogel aided by light. In addition, all hydrogels containing pillar[5]arenes have demonstrated biocompatibility and effectiveness as scaffolds for biological and medical purposes.

Silver(I) Sulfide Clusters Protected by Rhodium(III) Metalloligands with 3-Aminopropanethiolate.

The two homochiral AgIRhIII nanoclusters, Δ6/Λ6-[Ag11S{Rh(apt)3}6]9+ ([1]9+) and Δ6/Λ6-[Ag13S{Rh(apt)3}6]11+ ([2]11+), in which Ag11S and Ag13S cluster cores, respectively, are protected by fac-[Rh(apt)3] metalloligands, were newly synthesized from fac-[Rh(apt)3] (Hapt = 3-aminopropanethiol) and Ag+ in water in combination with sulfide sources. While [1]9+ was produced by using d-penicillamine as a sulfide source, the use of HS- as a sulfide source afforded [2]11+ without causing any precipitation of Ag2S. Cluster [1]9+ was convertible to [2]11+ via the reaction with Ag+, which led to a turn-on-type switch in photoluminescence from nonemissive [1]9+ to emissive [2]11+.

Jahn-Teller Switching of a Redox-Active Nickel(III) Center in a Homoleptic Thiolato Metalloligand Environment.

Treatment of nickel(II) nitrate with the iridium(III) metalloligand fac-[Ir(apt)3] (apt = 3-aminopropanethiolate) gave the trinuclear complex [Ni{Ir(apt)3}2](NO3)3 ([1Ir](NO3)3), in which the nickel center has a formal oxidation state of +III. Chemical or electrochemical oxidation and reduction of [1Ir](NO3)3 generated the corresponding trinuclear complexes [Ni{Ir(apt)3}2](NO3)4 ([1Ir](NO3)4) and [Ni{Ir(apt)3}2](NO3)2 ([1Ir](NO3)2) with one-electron oxidated and reduced states, respectively. Single-crystal X-ray crystallography revealed that the nickel center in [1Ir](NO3)3 is situated in a highly distorted octahedron due to Jahn-Teller effect, while the nickel center in each of [1Ir](NO3)4 and [1Ir](NO3)2 adopts a normal octahedral geometry. Crystals of [1Ir](NO3)3·2H2O are dehydrated on heating while retaining their single-crystallinity. The dehydration induces temperature-dependent dynamic disorder of the Jahn-Teller distortion at the nickel(III) center, which is largely quenched upon rehydration of the crystal.

Serendipitous formation of oxygen-bridged CuII6M (M = MnII, CoII) double cubanes showing electrocatalytic water oxidation.

Hydroxido-bridged CuII6M double-cubane clusters (M = MnII, CoII) supported by D-penicillaminedisulfide were unexpectedly formed by treating a D-penicillaminato CuII2PtII2 complex with MBr2 in water. The clusters displayed heterogeneous electrocatalytic activities for water oxidation dependent on the central M shared by two CuII cubane units.

A chromotropic PtIIPdIICoII coordination polymer with dual electrocatalytic activity for water reduction and oxidation.

Here, we present a heterometallic coordination polymer that exhibits heterogeneous electrocatalytic activities for both water reduction and water oxidation. Treatment of the PtII2PdII2 tetranuclear complex [Pd2{Pt(NH3)2(D-pen)2}2] ([1]; D-H2pen = D-penicillamine) with CoX2 (X = Cl, Br) provided (PtII2PdII2CoII2)n coordination polymers [Co2(H2O)6(1)]X4 ([2]X4), in which the PtII2PdII2 units of [1] are linked by [Co2(µ-H2O)(H2O)5]4+ moieties in a 3D network structure. [2]X4 showed a colour change from orange to dark green upon dehydration, reflecting the geometrical conversion of the CoII centres in [Co2(µ-H2O)(H2O)5]4+ from an octahedron to a tetrahedron by the removal of aqua ligands. While both [2]Cl4 and [2]Br4 electrochemically catalysed water reduction to H2 in the solid state due to the presence of PdII active centres, water oxidation to O2 was catalysed only by [2]Br4, which is ascribed to the presence of Br- ions that mediate the catalytic reactions that occurred at CoII active centres.

A mesoporous ionic solid with 272 AuI 6AgI 3CuII 3 complex cations in a super huge crystal lattice.

Here, we report a unique mesoporous ionic solid (I) generated from a cationic AuI 6AgI 3CuII 3 dodecanuclear complex with d-penicillamine depending on the homochirality and crystallization conditions. I crystallizes in the cubic space group of F4132 with an extremely large cell volume of 2 171 340 Å3, containing 272 AuI 6AgI 3CuII 3 complex cations in the unit cell. In I, the complex cations are connected to each other through CH⋯π interactions in a zeotype framework, the topology of which is the same as that of the metal-organic framework in MIL-101, with similar but much larger two types of polyhedral pores with internal diameters of 38.2 Å and 49.7 Å, which are occupied by counter-anions and water molecules. Due to the cationic nature of the framework, I undergoes quick, specific exchanges of counter-anions while retaining its single crystallinity. This study realized the creation of a non-covalent mesoporous framework from a single complex salt, providing a conceptual advance in solid chemistry and material science.

Highly Porous Ionic Solids Consisting of AuI3CoIII2 Complex Anions and Aqua Metal Cations.

Treatment of Na3[Au3Co2(d-pen)6] (Na3[1]; d-H2pen = d-penicillamine) with M(OAc)2 (M = NiII, MnII) in water gave ionic crystals of [M(H2O)6]3[1]2 (2M) in which [1]3- anions are hydrogen-bonded with [M(H2O)6]2+ cations to form a 3D porous framework with a porosity of ca. 80%. Soaking crystals of 2Ni in its mother liquor afforded crystals of [Ni(H2O)6]2[{Ni(H2O)4}(1)2] (3Ni) in which [1]3- anions are connected to trans-[Ni(H2O)4]2+ and [Ni(H2O)6]2+ cations through coordination and hydrogen bonds, respectively, to form a 1D porous framework with a porosity ca. 60%. Further soaking crystals led to [{Ni(H2O)4}3(1)2] (4Ni), in which [1]3- anions are connected to cis-[Ni(H2O)4]2+ and trans-[Ni(H2O)4]2+ cations through coordination bonds in a dense framework with a porosity of ca. 30%. A similar two-step crystal-to-crystal transformation mediated by solvent proceeded when crystals of 2Mn were soaked in a mother liquor. However, the transformation of 2Mn generated [{Mn(H2O)4}(H1)] (4'Mn) as the final product, in which [H1]2- anions are connected to cis-[Mn(H2O)4]2+ cations through coordination bonds in a very dense framework with a porosity ca. 5% by way of [Mn(H2O)6]2[{Mn(H2O)4}(1)2] (3Mn), which is isostructural with 3Ni. While all the compounds adsorbed H2O and CO2 depending on the degree of their porosity, unusually large NH3 adsorption capacities were observed for 4Ni and 4'Mn, which have dense frameworks.

Heterometallation of Photoluminescent Silver(I) Sulfide Nanoclusters Protected by Octahedral Iridium(III) Thiolates.

The recently-increasing interest in coinage metal clusters stems from their photophysical properties, which are controlled via heterometallation. Herein, we report homometallic AgI 46 S13 clusters protected by octahedral fac-[Ir(aet)3 ] (aet=2-aminoethanethiolate) molecules and their conversion to heterometallic AgI 43 MI 3 S13 (M=Cu, Au) clusters. The reactions of fac-[Ir(aet)3 ] with Ag+ and penicillamine produced [Ag46 S13 {Ir(aet)3 }14 ]20+ ([1]20+ ), where a spherical AgI 46 S13 cluster is covered by fac-[Ir(aet)3 ] octahedra through thiolato bridges. [1]20+ was converted to [Ag43 M3 S13 {Ir(aet)3 }14 ]20+ ([1M ]20+ ) with an AgI 43 MI 3 S13 cluster by treatment with M+ , retaining its overall structure. [1]20+ was photoluminescent and had an emission band ca. 690 nm that originated from an S-to-Ag charge transfer. While [1Cu ]20+ showed an emission band with a slightly higher energy of ca. 650 nm and a lower quantum yield, the emission band for [1Au ]20+ shifted to a much higher energy of ca. 590 nm with an enhanced quantum yield.

Intermediate snapshots of a 116-nuclear metallosupramolecular cage-of-cage in a homogeneous single-crystal-to-single-crystal transformation.

Soaking crystals of an AuI72CdII40NaI4 cage-of-cage in aqueous Co(NO3)2 afforded an analogous AuI72CoII44 cage-of-cage, accompanied by the exchange of NaI and CdII by CoII with retention of the single crystallinity. The homogeneous progress of the transformation led to the direct observation of intermediate species by single-crystal X-ray crystallography.

Transformations of empty Cu core to CuCuO and CuS cores via oxide and sulfide insertions.

[Cu4(LRh)4]8- ([1]8-; LRh = Δ-[Rh(l-cysteinate)3]3-), with an empty tetrahedral {CuI4}4+ core, was converted to [Cu4O(LRh)4]8- ([2]8-), with a mixed-valent {CuI2CuII2O}4+ core, in aqueous NaOH. A solid sample of the latter compound was converted back to [1]8- by heating under vacuum, while treatment of [1]8- with aqueous NaSH caused conversion to [Cu6S(LRh)4]8- ([3]8-), with a stable octahedral {CuI6S}4+ core.

Racemic Tartrate/Malate Anions Combine with Racemic Complex Cations to Form Optically Active Ionic Crystals.

Spontaneous resolution has attracted continuing attention in various research fields since Pasteur's work on the crystallization behavior of racemic tartrate. Here, a unique example of this phenomenon is reported, involving ionic crystals generated from racemic RR/SS- tartrate or R/S-malate and racemic ΔΔ/ΛΛ-[Ag3 Rh2 (2-aminoethanethiolato)6 ]3+ (ΔΔ/ΛΛ-[1]3+ ) in water. RR- and SS-tartrate selectively recognize the ΛΛ and ΔΔ isomers of [1]3+ to produce ionic crystals of (ΛΛ-[1])2 (RR-tartrate)3 and (ΔΔ-[1])2 (SS-tartrate)3 , respectively, which can undergo spontaneous resolution. While spontaneous resolution also occurs when using R/S-malate, R- and S-malate select the opposite isomers of [1]3+ to give ionic crystals of (ΔΔ-[1])2 (R-malate)3 and (ΛΛ-[1])2 (S-malate)3 , respectively. In the presence of S-aspartate, (ΛΛ-[1])2 (R-tartrate)3 and (ΔΔ-[1])2 (S-tartrate)3 are preferentially crystallized from ΔΔ/ΛΛ-[1]3+ and RR/SS-tartrate at solution pH values of 6 and 10, respectively. This finding provides significant insight into the optical resolution of chemical species by spontaneous resolution and the origin of homochirality in nature.

Insertion of a Hydride Ion Into a Tetrasilver(I) Cluster Covered by S-Donating Rhodium(III) Metalloligands.

Here, we report a tetrahedral silver(I) cluster of {Ag4}4+ covered by Δ-[Rh(l-cys)3]3- (l-H2cys = l-cysteine), which is converted to an {Ag4H}3+ cluster via the inclusion of a H- ion. The 1:1 reaction of Δ-[Rh(l-cys)3]3- with Ag+ gave a sulfur-bridged AgI4RhIII4 octanuclear structure in [Ag4{Rh(l-cys)3}4]8- ([1]8-), in which a tetrahedral {Ag4}4+ core is bound by four Δ-[Rh(l-cys)3]3- units through thiolato groups. DFT calculations revealed that a superatomic orbital exists in {Ag4}4+ as the lowest unoccupied molecular orbital, contributing to the appearance of a characteristic charge-transfer transition in the visible region for [1]8-. Treatment of [1]8- with NaBH4 led to the insertion of a H- ion to generate [Ag4H{Rh(l-cys)3}4]9- ([2]9-) with an {Ag4H}3+ core, accompanied by the disappearance of the visible band for [1]8-. The presence of a H- ion in the center of [2]9- was established by the 1H NMR spectrum, which reveals a unique quintuple-quintet signal from the H- ion surrounded by four AgI atoms. [2]9- was considerably stable in aqueous media, which is ascribed to a chemical bond between the unoccupied superatomic orbital of {Ag4}4+ and the occupied orbital of H- in the {Ag4H}3+ core.

A Dynamic Combinatorial Library of Cyclic AuI2NiII Complexes with Cysteine/Penicillamine Showing Solvent-Controlled Crystallization.

A dynamic combinatorial library (DCL) is a set of molecular species existing in equilibrium in solution that can undergo self-assembly via reversible chemical bonds. Here, we report a unique DCL system that shows the independent crystallization of products from solvents with slightly different polarities. The reaction of a 1:1 mixture of [Au2(dppm)(dl-cys)2]2- and [Au2(dppm)(dl-pen)2]2- with Ni2+ in solution gave a DCL containing 10 cyclic AuI2NiII molecules of [Au2Ni(dppm)(dl-cys/dl-pen)2]. Upon crystallization, three kinds of enantiomeric pairs, homoleptic-heterochiral C/A-[Au2Ni(dppm)(d-cys)(l-cys)], homoleptic-homochiral [Au2Ni(dppm)(d-pen)2]/[Au2Ni(dppm)(l-pen)2], and heteroleptic-homochiral [Au2Ni(dppm)(d-cys)(d-pen)]/[Au2Ni(dppm)(l-cys)(l-pen)], were produced from the reaction solutions of MeOH, MeOH/H2O, and EtOH/H2O, respectively. The independent crystallization was explained by a combination of the different hydrogen-bonding interactions of the AuI2NiII molecules in the crystal and the different thermodynamic stabilities of the molecules in solution.

Single-Crystal-to-Single-Crystal Installation of Ln4 (OH)4 Cubanes in an Anionic Metallosupramolecular Framework.

Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single-crystal-to-single-crystal (SCSC) transformation is presented. Soaking single crystals of K6 [Rh4 Zn4 O(l-cys)12 ] (K6 [1]; l-H2 cys=l-cysteine) in a water/ethanol solution containing Ln(OAc)3 (Ln3+ =lanthanide ion) results in the exchange of K+ by Ln3+ with retention of the single crystallinity, producing Ln2 [1] (2Ln ) and Ln0.33 [Ln4 (OH)4 (OAc)3 (H2 O)7 ][1] (3Ln ) for early and late lanthanides, respectively. While the Ln3+ ions in 2Ln exist as disordered aqua species, those in 3Ln form ordered hydroxide-bridged cubane clusters that connect [1]6- anions in a 3D metal-organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts.

Modulating the Magnetic Properties of Copper(II)/Nitroxyl Heterospin Complexes by Suppression of the Jahn-Teller Distortion.

A series of six-coordinate [Cu(L)L1][BF4]2 (L1 = 2,6-bis{1-oxyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-2-yl}pyridine) complexes are reported. Ferromagnetic coupling between the Cu and L1 ligand spins is enhanced by an L coligand with distal methyl substituents, which is attributed to a sterically induced suppression of its Jahn-Teller distortion.

Charge-Separation-Type Ionic Crystals with Mixed AuI4CoIII2 and AuI4NiIICoIII Hexanuclear Complexes.

Treatment of a digold(I) metalloligand, [AuI2(dppe)(d-Hpen)2] (H2LAu; d-H2pen = d-penicillamine, dppe = 1,2-bis(diphenylphosphino)ethane), with a 1:1 mixture of Co(OAc)2 and Ni(OAc)2 under aerobic conditions resulted in the formation of three types of hexanuclear complexes: [CoIII2(LAu)2]2+, [NiIICoIII(LAu)2]+, and [NiII2(LAu)2]. The addition of NaNO3, M1NO3 (M1 = K, Rb, Cs), and M2(NO3)2 (M2 = Ca, Sr, Ba) to the reaction mixture led to co-crystallization of [CoIII2(LAu)2]2+ and [NiIICoIII(LAu)2]+ as a solid solution to form the charge-separation (CS)-type ionic crystals 1Na, 1M1, and 1M2, respectively, while [NiII2(LAu)2] independently crystallized as a single species (2). In 1Na, [CoIII2(LAu)2]2+ and [NiIICoIII(LAu)2]+ cations assemble in a 1:2 ratio to form a cationic supramolecular octahedron accommodating 4 H3O+ ions, while 10 nitrate ions are packed in each hydrophilic tetrahedral interstice of the crystal to form an anionic adamantane cluster. The overall structures of 1M1 and 1M2 are very similar to that of 1Na, having a CS-type structure composed of cationic supramolecular octahedra with a +12 charge and anionic inorganic clusters with a -10 charge. However, 1M1 contains M1 ions in place of the H3O+ ions in 1Na, and furthermore, a novel rhombic dodecahedron cluster composed of 14 nitrate ions, which encapsulates two M2 ions, is formed in each hydrophilic tetrahedral interstice in 1M2.

Heterochiral-to-Homochiral Structural Transformation in Metallosupramolecular Ionic Crystals.

Here, we report a unique transformation from heterochiral to homochiral structures in ionic crystals composed of complex cations and complex anions. Treatment of an anionic AuI3CoIII2 complex, ΛΛ-[Au3Co2(d-pen)6]3- ([1]3-; H2pen = penicillamine), with M = MnII, CoII, NiII, ZnII in water in the presence of 1,10-phenanthroline (phen) commonly gave ionic crystals formulated as [M(phen)2(H2O)2][Na(H2O)6][{M(phen)2(H2O)}(1)]3 (2M), in which [M(phen)2(H2O)2]2+ and [M(phen)2(H2O)]2+ adopt Δ and Λ configurations, respectively. While 2Co, 2Ni, and 2Zn were all stable in each mother liquor, 2Mn was converted to [Mn(phen)3]3[1]2·phen (3Mn) containing the Λ configurational [Mn(phen)3]3+ under the same conditions. 3Mn showed a water adsorption capacity higher than that of 2Mn, despite its lower porosity of crystal.