Two ultrasmall gold clusters, Au13 and Au8, were identified as a distorted Ih icosahedral Au13 and edge-shared “core + 4exo” structure Au8S2 cores, respectively. They showed interesting luminescence and electrochemical properties.
A new 3D Ag(I)-based coordination network, [Ag2(pz)(bdc)·H2O]n (1; pz = pyrazine and H2bdc = benzene-1,3-dicarboxylic acid), was constructed by one-pot assembly and structurally established by single-crystal X-ray diffraction at different temperatures. Upon cooling from 298 to 93 K, 1 undergo an interesting single-crystal to single-crystal phase transition from orthorhombic Ibca (Z = 16) to Pccn (Z = 32) at around 148 K. Both phases show a rare 2-fold-interpenetrated 4-connected lvt network but incorporate different [Ag2(COO)2] dimeric secondary building units. It is worth mentioning that complex 1 shows red- and blue-shifted luminescences in the 290-170 and 140-80 K temperature ranges, respectively. The variable-temperature single-crystal X-ray crystallographic studies suggest that the argentophilic interactions and rigidity of the structure dominated the luminescence chromism trends at the respective temperature ranges. Upon being mechanically ground, 1 exhibits a slight mechanoluminescence red shift from 589 to 604 nm at 298 K.
Although there has been an upsurge of interest in anisotropic assembly of inorganic nanoparticles, atomically precise self-assembly of anisotropic metal clusters is extremely rare. Herein, we presented two novel silver nanoclusters, Ag (SD/Ag23) and Ag (SD/Ag24), which are interiorly templated by five MoO and a pair of MoO anions, respectively, and coprotected by bridging RSH and terminal diphosphine ligands exteriorly. Regiospecific distribution diphosphine ligands on the surface and the arrangement of multiple molybdate templates within the nanoclusters synergetically tailor their shapes to anisotropic oblate spheroid and elongated rod, respectively. This work not only open up new avenues for the synthesis of silver nanoclusters with novel metal skeleton shapes and anisotropic surface structures but also give important insights for the anisotropic growth of silver nanoclusters through surface modifications or/and template organizations.
An unprecedentedr eversible dynamic transformation is reported in am etal-organic framework involving bond formation, which is accompanied by two important structural changes;achiral to chiral and two-to three-dimensions. Using two bent organic ligands (diimpym = 4,6-di(1H-imidazol-1-yl)pyrimidine;H 2 npta = 5-nitroisophthalic acid) and Co II (NO 3 ) 2 ·6H 2 Ot he coordination polymer Co(diimpym)(npta)·CH 3 OH, (1·CH 3 OH), was obtained solvothermally. Its structure consists of knitted pairs of square layers (4 4 -sql net) of five-coordinated Co and disordered methanol, and it crystallizedi nt he achiral Pbca space group at room temperature. It undergoes as ingle crystal to single crystal (SC-SC) transformation to a3 Di nterpenetrated framework (a-polonium-type net, pcu)o fs ix-coordinated Co and ordered methanol in the chiral P2 1 2 1 2 1 space group below 220 K. Most unusual is the dynamic temperature-dependent shortening of aC o···O connection from an on-bonded 2.640 (298 K) to ab onded2 .347 distance (100 K) transforming the square pyramidal cobalt polyhedron to ad istorted octahedron. The desolvated crystals( 1)o btained at 480 Kr etain the full crystallinitya nd crystallize in the achiral Pbca space group between 100 and 298 Kb ut the dynamic shorteningo ft he Co···O distance connecting the layers into the 3D pcu framework structure is observed. Following post-synthetic insertion of ethanol (1·CH 3 CH 2 OH)i td oes not exhibit the transformation and retains the knitted2 Da chiral Pbca structure for all temperatures (100-298 K) and the ethanol is always disordered. The structurala nalyses thusc oncludet hat the ordering of the methanol induces the chirality while the availables pace controlst he dynamic motion of the knitted 2D networks into the 3D interpenetrated framework. Consequently, 1 selectively adsorbs CO 2 to N 2 and exhibits Type-III isotherms indicating dynamic motion of the 2D networks to accommodate the CO 2 at 273 and 298 Ki nc ontrast to the rigidity of the 3D framework at 77 Kp reventing N 2 from penetrating the solid. The magnetic properties are also reported.
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