Systematic control of the photophysical properties of metal nanoclusters (NCs) through ligand design is a powerful strategy for future nanomaterials. In this study, we synthesized silver NCs with improved photoluminescence (PL) properties via surface-ligand engineering. We derivatized 3,5-dimercaptobenzoic acid (DMBA) with tethering a naphthalene ring via an amide linkage to form the BDT-Naph ligand. The use of BDT-Naph ligand with the aid of tetraphenylphosphine (PPh3) as a subligand yielded luminescent silver NCs with the composition of [Ag29(BDT-Naph)12(PPh3)4]3- (Ag 29 -BDTN). The solubility of Ag29 NCs could be controlled with the choice of countercations of the trianionic NC, such as Na+, tetrabutylammonium (TBA), and tetraoctylammonium (TOA) cations. Ag 29 -BDTN NCs exhibited an improved photoluminescence quantum yield (PLQY) of 34% in THF compared to Ag29 NCs carrying unmodified 3,5-benzenedithiol (BDT) with the composition of [Ag29(BDT)12(PPh3)4]3- (Ag 29 -BDT, PLQY: 6%) in the same solvent. Furthermore, stable aqueous dispersions of Ag 29 -BDTN NC aggregates maintaining a relatively high PLQY (24%) were obtained through a simple dilution of THF solution by water. It is worth noting that the emissive aggregates could be lyophilized into a powder and subsequently fully dispersed in water.

In the p-toluenethiolate-bridged diplatinum complex bearing ethylene-bridged bis(N-heterocyclic carbene) ligands, all four acetyl-protected glucopyranosyl wingtip substituents adopt the chair conformation, giving rise to an open structure around the Pt2S2 core that allows the complex to react with a Grignard reagent. In contrast, in the corresponding diplatinum complex with o-xylene-bridged bis(N-heterocyclic carbene) ligands, two of the four acetyl-protected glucopyranosyl groups adopt the twist-boat conformation to relieve the steric repulsion among the wingtip N-substituents, resulting in a covered structure around the Pt2S2 core that inhibits reaction with a Grignard reagent.

Understanding the magnetic interactions within gold clusters that involve superatomic orbitals is critically important in advancing the development of nanoscale materials with magnetic functionality. In this study, we report on the synthesis of Ir-doped Au12 (Ir@Au12) icosahedral clusters functionalized with two open-shell verdazyl radicals at opposite poles, along with an investigation into their electronic, magnetic, and photophysical properties. The photoluminescence from the Ir@Au12 cluster core is drastically quenched by the introduction of verdazyl ligands. The ultrafast time-resolved absorption spectroscopy reveals the electron transfer from the Ir@Au12 core in the triplet excited state to the verdazyl ligand. The EPR study discloses the hyperfine coupling with the Au and Ir nuclei, indicating the spin density of the verdazyl radical moderately delocalized over the Ir@Au12 core. These results provide direct evidence of electronic interaction between the organic radicals and Ir@Au12 superatomic core. Furthermore, the variable temperature EPR study suggests weak magnetic communication between the two verdazyl radical ligands mediated by the Ir@Au12 superatomic core. These findings will establish superatom-organic radical hybrids as a new class of multi-spin systems and provide a design strategy for photofunctional and magnetic nanomaterials based on atomically precise metal clusters.

The assembly of metal nanoclusters (NCs) into crystalline lattice structures is of interest in the development of NC-based functional materials. Here we demonstrate that the assembled structures of tri-anionic tetrahedral symmetric [Ag29(BDT)12]3- (Ag29 NC, BDT: 1,3-benzenedithiol) NCs are controlled into a polyethylene-like zigzag chain and a "poly-ring-fused-cyclohexane"-like honeycomb arrangement through ionic interactions with alkali metal cations such as K+ and Cs+. The site-specific binding of alkali metal ions on the tetrahedrally arranged binding sites of Ag29 NCs successfully connects the adjacent NCs into various packing modes. The number and type of bridges between NCs determine the Ag29 NC packing structures, which are affected by the solvent species, enabling the transformation of packing modes in the single-crystalline state. The photoluminescence (PL) properties of the crystals responded to the packing modes of the NCs in terms of anisotropy and bridge linkage style inducing a varied degree of relaxation of the excited state depending on the relocation mobility of alkali metal ions in the crystals. Site-specific linkage of tri-anionic silver nanoclusters with tetrahedrally arranged bridging sites by alkali metal counter cations leads to various network structures.

Linkage isomers of homoleptic complexes, [RhIII(SCN)6]3- and [RhIII(NCS)(SCN)5]3-, formed in aqueous solution were successfully separated by employing methyltriphenylphosphonium (MePPh3+) and 1-ethylquinolinium (EtQu+) ions as countercations, respectively. The single-crystal X-ray analysis of (MePPh3)3[RhIII(SCN)6] (1) indicated that all of the SCN- ligands coordinate to the RhIII ion by S atoms with an octahedral symmetry, where the average bond length of Rh-S is 2.374(7) Å. On the other hand, the RhIII ion of (EtQu)3[RhIII(NCS)(SCN)5]·H2O (2) is coordinated by five S atoms and one N atom of the SCN- ligands with a C4v symmetry. Structural trans influence was observed in the shorter bond length of Rh-S at the trans position of Rh-N. The Rh-S bond length is 2.3398(13) Å significantly shorter than those of 1 by ca. 0.04 Å, although DFT calculations based on the crystal structures indicated that the effective bond order of Rh-N is higher than those of Rh-S. Thermal stability examination by thermogravimetric and differential thermal analyses (TG/DTA) and IR spectroscopy indicated that the linkage isomerization of [RhIII(SCN)6]3- to [RhIII(NCS)(SCN)5]3- proceeded after melting around 174 °C. These results clearly indicate that [RhIII(NCS)(SCN)5]3- is thermodynamically more stable than [RhIII(SCN)6]3- in solid states, although further linkage isomerization hardly occurs.

Sample dependence of dimensionless thermoelectric figure of merit ( zT ) and power factor ( PF ) were determined for the non-stoichiometric organic conductor (TTT) 2 I 3 + (cid:14) (TTT = tetrathiatetracene, (cid:14) (cid:20) 0 : 1) with the simultaneous measurement of the electrical resistivity ( (cid:26) ), thermopower ( S ) and thermal conductivity on small single crystals. Both the zT and PF show large sample dependence between 10 and 310 K, even though all the samples have nearly stoichiometric composition of TTT:I (cid:0) 3 (cid:24) 2:1 ( (cid:14) (cid:24) 0). It was found that both the electrical conductivity ( (cid:27) = 1 =(cid:26) ) and S increase at room temperature as disorder — that is phase mismatch among the iodine chains — becomes more pronounced. This behavior contrasts the usual tendency that the S decreases as the (cid:27) increases in conventional conductors; and suggests a new strategy to improve the

The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag29(BDT)12(TPP)4]3- NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region. The binding of silver(I) complexes to the peripheral region of Ag29 NC is confirmed by the single-crystal X-ray diffraction (SCXRD) measurement, which is further supported by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The change of excited-state dynamics by the binding of silver(I) complexes is discussed based on the results of a transient absorption study as well as temperature-dependent PL spectra and PL lifetime measurements. The modification of Ag29 NCs with cationic silver(I) complexes is considered to give rise to a triplet excited state responsible for the intense NIR PL. These findings also afford important insights into the origin of the PL mechanism as well as the possible light-driven motion in Ag29-based NCs.

We designed and synthesized a triphenylphenylnitroxide-(nitronyl nitroxide) dyad with a structure isoelectronic with trimethylenemethane. Crystal structure analysis demonstrated that the dihedral angle between the nitroxide and nitronyl nitroxide moieties was excessively small due to the steric effects of the triphenylphenyl moiety. The coplanarity of the two radical systems induced an excessively strong ferromagnetic intramolecular interaction (2J/k(B) >= +2000K; H = -2JS(1/2)center dot S-1/2).

X-ray structure analyses of co-crystals of H 2 O 2 and l -Phe, dl -Phe, or dl -Asp prepared in a dilute aqueous solution (30 wt%) indicated that multi-layer motifs including water molecule is important for highly efficient H 2 O 2 capture in dilute solutions.

We prepared dicopper, disilver, and tetragold clusters ligated with (nitronyl nitroxide)-substituted amidinate (NN-amidinate). NN-substituted amidine was prepared fromN,N '-diphenylcarbodiimide via a nucleophilic reaction with nitronyl nitroxide as a radical anion. The NN-amidinate ligand was generated by treatment with an appropriate base, and subsequent addition of copper(I), silver(I), or gold(I) sources gave the respective metal cluster systems of Cu-2-(NN-amidinate)(2), Ag-2-(NN-amidinate)(2), or Au-4-(NN-amidinate)(4). These radical-metal clusters exhibited excellent stability, even in solution under aerated conditions, making them easy to handle. Single crystals were obtained by recrystallization from suitable solvent systems. The spin structures of the cluster systems were investigated by ESR spectroscopy and magnetic susceptibility measurements, which indicated the existence of weak intramolecular, spin-spin interactions between the NN moieties.

A nitronyl nitroxide unit (NN) was linked with a triphenylamine-based condensed polycyclic skeleton DOTT to form a radical substituted donor NN-DOTT. X-ray crystal structure analysis demonstrated a flat bowl shape of the DOTT unit. EPR spectra showed the localization of electron spin on the NN unit. Chemical oxidation of the DOTT unit produced radical-substituted radical cation salts NN-DOTT+  ⋅ SbF6 - and NN-DOTT+  ⋅ FeBr4 - that are stable under ambient conditions. The magnetic behavior of NN-DOTT+  ⋅ SbF6 - is characterized by the strong intramolecular ferromagnetic interaction between NN and DOTT+ . The X-ray structural analysis of NN-DOTT+  ⋅ FeBr4 - shows planar structure of DOTT and 1D mixed-stack column of NN-DOTT+ and FeBr4 - . Magnetic measurements established that NN-DOTT+  ⋅ FeBr4 - undergoes magnetic phase transition into a weak ferromagnet at 7 K.

Sample dependence of dimensionless thermoelectric figure of merit (zT) and power factor (PF) were determined for the non-stoichiometric organic conductor (TTT)(2)I3+delta (TTT = tetrathiatetracene, delta <= 0.1) with the simultaneous measurement of the electrical resistivity (rho), thermopower (S) and thermal conductivity on small single crystals. Both the zT and PF show large sample dependence between 10 and 310 K, even though all the samples have nearly stoichiometric composition of TTT : I-3(-) similar to 2 : 1 (delta similar to 0). It was found that both the electrical conductivity (sigma = 1/rho) and S increase at room temperature as disorder-that is phase mismatch among the iodine chains-becomes more pronounced. This behavior contrasts the usual tendency that the S decreases as the s increases in conventional conductors; and suggests a new strategy to improve the zT and PF by introducing an appropriate type of disorder.

A series of thiocyanato-bridged heterometallic coordination polymers with a 3D reticular network have been synthesised by the reaction of [PtIV(SCN)6]2- with MII ions to form {MII[PtIV(SCN)6]}n and {[MII(CH3OH)2][PtIV(SCN)6]}n (MII = MnII, FeII, CoII, NiII or CuII) in water and methanol, respectively. Single-crystal X-ray analyses revealed the absence of open metal sites in {MII[PtIV(SCN)6]}ns and the formation of potential open metal sites at the MII ions of {[MII(CH3OH)2][PtIV(SCN)6]}ns by the coordination of methanol. One of the two coordinating methanol molecules in {[CoII(CH3OH)2][PtIV(SCN)6]}n was replaced with pyridine to stabilise the open metal sites, because the methanol molecules are too labile to maintain open metal sites in water. The heterogeneous catalysis of coordination polymers with and without open metal sites was examined for organophosphate hydrolysis and photocatalytic water oxidation to clarify the requisites for heterogeneous catalysts.

A triplet ground-state diradical molecule, bis(nitronyl nitroxide)-substituted diphenyldihydrophenazine (1(..)), that can be converted into a one-electron oxidized species, 1( horizontal ellipsis +), in the quartet ground state has been developed. Surprisingly, these species, 1(..) and 1( horizontal ellipsis +), can be used under ambient conditions because they are reasonably stable under aerobic conditions, even in solution. The temperature-dependent magnetic susceptibilities reveal that 1(..) and 1( horizontal ellipsis +) are in the triplet state, with a weak exchange interaction (J(1)/k(B) = +3.1 K) and quartet ground state with a strong exchange interaction (J(2)/k(B) = +160 K), respectively. The interconversion between the neutral and one-electron oxidized species can be realized through electrochemical reactions. Significantly different absorption bands in the near-IR region newly appeared in the electronic spectra acquired during electrochemical oxidation/reduction.