8 research outputs found
The 5f2--5f16d1 absorption spectrum of Cs2GeF6:U4+ crystals: a quantum chemical and experimental study
The luminescence properties of three tetrakis dibenzoylmethane europium(III) complexes with different counter ions
The luminescence properties of three tetrakis dibenzoylmethane europium(III) complexes with different counter ions
The 5f2â5f16d1 absorption spectrum of Cs2GeF6:U4+ crystals: A quantum chemical and experimental study
Ag<sup>I</sup>/V<sup>V</sup> Heterobimetallic Frameworks Generated from Novel-Type {Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(triazole)<sub>4</sub>} Secondary Building Blocks: A New Aspect in the Design of SVOF Hybrids
A series of new silverÂ(I)-containing MOFs [Ag<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>ad</i>)<sub>2</sub>]Â(ClO<sub>4</sub>)<sub>2</sub> (<b>1</b>), [Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>ad</i>)<sub>2</sub>]·H<sub>2</sub>O (<b>2</b>), [Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>eth</i>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>3</b>), and [Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>cy</i>)<sub>2</sub>]·4H<sub>2</sub>O (<b>4</b>) supported by 4-substituted
bifunctional 1,2,4-triazole ligands (<i>tr</i><sub><i>2</i></sub><i>ad</i> = 1,3-bisÂ(1,2,4-triazol-4-yl)Âadamantane, <i>tr</i><sub><i>2</i></sub><i>eth</i> = 1,2-bisÂ(1,2,4-triazol-4-yl)Âethane, <i>tr</i><sub><i>2</i></sub><i>cy</i> = <i>trans</i>-1,4-bisÂ(1,2,4-triazol-4-yl)Âcyclohexane) were hydrothermally
synthesized and structurally characterized. In these complexes, the
triazole heterocycle as an N<sup>1</sup>,N<sup>2</sup>-bridge links
either two adjacent AgâAg or AgâV centers at short distances
forming polynuclear clusters. The crystal structure of compound <b>1</b> is based on cationic {Ag<sub>2</sub>(<i>tr</i>)<sub>4</sub>}<sup>2+</sup> fragments connected in a 2D rhombohedral
grid network with (4,4) topology. The neighboring layers are tightly
packed into a 3D array by means of argentophilic interactions (Ag···Ag
3.28 Ă
). Bridging between different metal atoms through the triazole
groups assists formation of heterobimetallic Ag<sup>I</sup>/V<sup>V</sup> secondary building blocks in a linear VâAgâAgâV
sequence that is observed in complexes <b>2</b>â<b>4</b>. These unprecedented tetranuclear {Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i>)<sub>4</sub>} units (the intermetal AgâAg and AgâV distances are
4.24â4.36 and 3.74â3.81 Ă
, respectively), in which
vanadiumÂ(V) oxofluoride units possess distorted trigonal bipyramidal
environment {VO<sub>2</sub>F<sub>2</sub>N}ÂŻ, are incorporated
into 1D ribbon (<b>2</b>) or 2D square nets (<b>3</b>, <b>4</b>) using bitopic Ό<sub>4</sub>-triazole ligands. The
valence bond calculation for vanadium atoms shows +V oxidation state
in the corresponding compounds. Thermal stability and photoluminescence
properties were studied for all reported coordination polymers
Ag<sup>I</sup>/V<sup>V</sup> Heterobimetallic Frameworks Generated from Novel-Type {Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(triazole)<sub>4</sub>} Secondary Building Blocks: A New Aspect in the Design of SVOF Hybrids
A series of new silverÂ(I)-containing MOFs [Ag<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>ad</i>)<sub>2</sub>]Â(ClO<sub>4</sub>)<sub>2</sub> (<b>1</b>), [Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>ad</i>)<sub>2</sub>]·H<sub>2</sub>O (<b>2</b>), [Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>eth</i>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>3</b>), and [Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i><sub><i>2</i></sub><i>cy</i>)<sub>2</sub>]·4H<sub>2</sub>O (<b>4</b>) supported by 4-substituted
bifunctional 1,2,4-triazole ligands (<i>tr</i><sub><i>2</i></sub><i>ad</i> = 1,3-bisÂ(1,2,4-triazol-4-yl)Âadamantane, <i>tr</i><sub><i>2</i></sub><i>eth</i> = 1,2-bisÂ(1,2,4-triazol-4-yl)Âethane, <i>tr</i><sub><i>2</i></sub><i>cy</i> = <i>trans</i>-1,4-bisÂ(1,2,4-triazol-4-yl)Âcyclohexane) were hydrothermally
synthesized and structurally characterized. In these complexes, the
triazole heterocycle as an N<sup>1</sup>,N<sup>2</sup>-bridge links
either two adjacent AgâAg or AgâV centers at short distances
forming polynuclear clusters. The crystal structure of compound <b>1</b> is based on cationic {Ag<sub>2</sub>(<i>tr</i>)<sub>4</sub>}<sup>2+</sup> fragments connected in a 2D rhombohedral
grid network with (4,4) topology. The neighboring layers are tightly
packed into a 3D array by means of argentophilic interactions (Ag···Ag
3.28 Ă
). Bridging between different metal atoms through the triazole
groups assists formation of heterobimetallic Ag<sup>I</sup>/V<sup>V</sup> secondary building blocks in a linear VâAgâAgâV
sequence that is observed in complexes <b>2</b>â<b>4</b>. These unprecedented tetranuclear {Ag<sub>2</sub>(VO<sub>2</sub>F<sub>2</sub>)<sub>2</sub>(<i>tr</i>)<sub>4</sub>} units (the intermetal AgâAg and AgâV distances are
4.24â4.36 and 3.74â3.81 Ă
, respectively), in which
vanadiumÂ(V) oxofluoride units possess distorted trigonal bipyramidal
environment {VO<sub>2</sub>F<sub>2</sub>N}ÂŻ, are incorporated
into 1D ribbon (<b>2</b>) or 2D square nets (<b>3</b>, <b>4</b>) using bitopic Ό<sub>4</sub>-triazole ligands. The
valence bond calculation for vanadium atoms shows +V oxidation state
in the corresponding compounds. Thermal stability and photoluminescence
properties were studied for all reported coordination polymers
Triazolyl, Imidazolyl, and Carboxylic Acid Moieties in the Design of Molybdenum Trioxide Hybrids: Photophysical and Catalytic Behavior
Three
organic ligands bearing 1,2,4-triazolyl donor moieties, (<i>S</i>)-4-(1-phenylpropyl)-1,2,4-triazole (<i>trethbz</i>), 4-(1,2,4-triazol-4-yl)Âbenzoic
acid (<i>trPhCO</i><sub>2</sub><i>H</i>), and
3-(1<i>H</i>-imidazol-4-yl)-2-(1,2,4-triazol-4-yl)Âpropionic
acid (<i>trhis</i>), were prepared to evaluate their coordination
behavior in the development of molybdenumÂ(VI) oxide organic hybrids.
Four compounds, [Mo<sub>2</sub>O<sub>6</sub>(<i>trethbz</i>)<sub>2</sub>]·H<sub>2</sub>O (<b>1</b>), [Mo<sub>4</sub>O<sub>12</sub>(<i>trPhCO</i><sub>2</sub><i>H</i>)<sub>2</sub>]·0.5H<sub>2</sub>O (<b>2a</b>), [Mo<sub>4</sub>O<sub>12</sub>(<i>trPhCO</i><sub>2</sub><i>H</i>)<sub>2</sub>]·H<sub>2</sub>O (<b>2b</b>), and
[Mo<sub>8</sub>O<sub>25</sub>(<i>trhis</i>)<sub>2</sub>(<i>trhisH</i>)<sub>2</sub>]·2H<sub>2</sub>O (<b>3</b>), were synthesized and characterized. The monofunctional <i>tr</i>-ligand resulted in the formation of a zigzag chain [Mo<sub>2</sub>O<sub>6</sub>(<i>trethbz</i>)<sub>2</sub>] built
up from <i>cis-</i>{MoO<sub>4</sub>N<sub>2</sub>} octahedra
united through common Ό<sub>2</sub>-O vertices. Employing the
heterodonor ligand with <i>tr/âCO</i><sub>2</sub><i>H</i> functions afforded either layer or ribbon structures
of corner- or edge-sharing {MoO<sub>5</sub>N} polyhedra (<b>2a</b> or <b>2b</b>) stapled by <i>tr</i>-links in axial
positions, whereas âCO<sub>2</sub>H groups remained uncoordinated.
The presence of the <i>im-</i>heterocycle as an extra function
in <i>trhis</i> facilitated formation of zwitterionic molecules
with a protonated imidazolium group (<i>imH</i><sup><i>+</i></sup>) and a negatively charged âCO<sub>2</sub><sup>â</sup> group, whereas the <i>tr-</i>fragment
was left neutral. Under the acidic hydrothermal conditions used, the
organic ligand binds to molybdenum atoms either through [NâN]-<i>tr</i> or through both [NâN]-<i>tr</i> and
ÎŒ<sub>2</sub>-CO<sub>2</sub><sup>â</sup> units, which
occur in protonated bidentate or zwitterionic tetradentate forms (<i>trhisH</i><sup><i>+</i></sup> and <i>trhis</i>, respectively). This leads to a new zigzag subtopological motif
(<b>3</b>) of negatively charged polyoxomolybdate {Mo<sub>8</sub>O<sub>25</sub>}<sub><i>n</i></sub><sup>2<i>n</i>â</sup> consisting of corner- and edge-sharing <i>cis-</i>{MoO<sub>4</sub>N<sub>2</sub>} and {MoO<sub>6</sub>} octahedra, while
the tetradentate zwitterrionic <i>trhis</i> species connect
these chains into a 2D net. Electronic spectra of the compounds showed
optical gaps consistent with semiconducting behavior. The compounds
were investigated as epoxidation catalysts via the model reactions
of achiral and prochiral olefins (<i>cis</i>-cyclooctene
and <i>trans</i>-ÎČ-methylstyrene) with <i>tert</i>-butylhydroperoxide. The best-performing catalyst (<b>1</b>) was explored for the epoxidation of other olefins, including biomass-derived
methyl oleate, methyl linoleate, and prochiral dl-limonene