15 research outputs found
Zinc Complexes Supported by Maltolato Ligands: Synthesis, Structure, Solution Behavior, and Application in Ring-Opening Polymerization of Lactides
A series of novel zinc alkoxides supported by chelating
maltolato
(MalO; MalOH = maltol) ligands were successfully synthesized and characterized.
Reaction of MalOH with ZnEt<sub>2</sub> (3:4) gives a trinuclear cluster
[Zn<sub>3</sub>(Et)<sub>2</sub>(MalO)<sub>4</sub>] (<b>1</b>), which spontaneously disproportionates in solution to mononuclear
species [Zn(MalO)<sub>2</sub>] (<b>1a</b>) and [Zn(Et)(MalO)]
(<b>1b</b>); (<b>1a</b>) and (<b>1b</b>) form [Zn(MalO)<sub>2</sub>(py)] (<b>2</b>), [Zn(Et)(MalO)(py)] (<b>3</b>), [Zn(MalO)<sub>2</sub>]<sub>2</sub> (<b>(1a)<sub>2</sub></b>), [Zn(MalO)(OBn)]<sub>2</sub> (<b>(1c)<sub>2</sub></b>), and
[Zn<sub>4</sub>(Et)<sub>2</sub>(OEt)<sub>2</sub>(MalO)<sub>4</sub>] (<b>4</b>) on addition of pyridine, benzyl alcohol (BnOH),
or dry O<sub>2</sub>, respectively. Compounds <b>1</b>, <b>2</b>, <b>(1a)</b><sub><b>2</b></sub>, and <b>4</b> were characterized by elemental analysis, NMR, ESI-MS, and single-crystal
X-ray structural analysis. Variable-temperature NMR experiments showed
that <b>(1a)</b><sub><b>2</b></sub> and <b>(1c)</b><sub><b>2</b></sub> are in equilibrium with the monomeric form
in solution. The addition of l-lactide (l-LA) to
a combination of <b>1</b> and 2 equiv of BnOH in dichloromethane
at room temperature in different molar ratios leads to rapid and efficient
generation of poly(l-LA) with end-capped BnO groups. According
to kinetic studies, propagation by [Zn(OBn)(MalO)] (<b>1c</b>) is first-order with respect to both the monomer and <b>1c</b> concentrations; <b>1a</b> in ring-opening polymerization of l-LA shows no activity. These results suggest a single-site
active species in the ring-opening polymerization of l-LA
Zinc Complexes Supported by Maltolato Ligands: Synthesis, Structure, Solution Behavior, and Application in Ring-Opening Polymerization of Lactides
A series of novel zinc alkoxides supported by chelating
maltolato
(MalO; MalOH = maltol) ligands were successfully synthesized and characterized.
Reaction of MalOH with ZnEt<sub>2</sub> (3:4) gives a trinuclear cluster
[Zn<sub>3</sub>(Et)<sub>2</sub>(MalO)<sub>4</sub>] (<b>1</b>), which spontaneously disproportionates in solution to mononuclear
species [Zn(MalO)<sub>2</sub>] (<b>1a</b>) and [Zn(Et)(MalO)]
(<b>1b</b>); (<b>1a</b>) and (<b>1b</b>) form [Zn(MalO)<sub>2</sub>(py)] (<b>2</b>), [Zn(Et)(MalO)(py)] (<b>3</b>), [Zn(MalO)<sub>2</sub>]<sub>2</sub> (<b>(1a)<sub>2</sub></b>), [Zn(MalO)(OBn)]<sub>2</sub> (<b>(1c)<sub>2</sub></b>), and
[Zn<sub>4</sub>(Et)<sub>2</sub>(OEt)<sub>2</sub>(MalO)<sub>4</sub>] (<b>4</b>) on addition of pyridine, benzyl alcohol (BnOH),
or dry O<sub>2</sub>, respectively. Compounds <b>1</b>, <b>2</b>, <b>(1a)</b><sub><b>2</b></sub>, and <b>4</b> were characterized by elemental analysis, NMR, ESI-MS, and single-crystal
X-ray structural analysis. Variable-temperature NMR experiments showed
that <b>(1a)</b><sub><b>2</b></sub> and <b>(1c)</b><sub><b>2</b></sub> are in equilibrium with the monomeric form
in solution. The addition of l-lactide (l-LA) to
a combination of <b>1</b> and 2 equiv of BnOH in dichloromethane
at room temperature in different molar ratios leads to rapid and efficient
generation of poly(l-LA) with end-capped BnO groups. According
to kinetic studies, propagation by [Zn(OBn)(MalO)] (<b>1c</b>) is first-order with respect to both the monomer and <b>1c</b> concentrations; <b>1a</b> in ring-opening polymerization of l-LA shows no activity. These results suggest a single-site
active species in the ring-opening polymerization of l-LA
Solvothermal Alcoholysis Routes for Recycling Polylactide Waste as Lactic Acid Esters
In
this work, we investigated the possible use of polylactide (PLA),
a biodegradable polymer obtained from renewable biofeedstock, to produce
a range of industrially useful lactic acid esters. We describe a simple
and convenient solvothermal alcoholysis method for large-scale recycling
of PLA resins or residues from disposable packaging in the presence
of the appropriate alcohol under catalyst-free or catalytic conditions.
This process proceeds easily both without and with a catalyst. The
results show that the best catalytic activities involve magnesium
and calcium alkoxides synthesized in situ from organometallic or metallic
precursors and an alcohol. We determined the crystal structure of
the chiral mononuclear postcatalyst [Ca(LAc)<sub>2</sub>(EL)<sub>2</sub>] (<b>1</b>; LAc = lactic acid anion, EL = ethyl lactate),
obtained directly from the reactor. Particular emphasis is placed
on the operating conditions and high activity of the catalyst used.
Key factors that affect the catalytic activity and reaction mechanism
are also highlighted
Synthesis of Aluminosilicates Containing a Ba(Sr)–O–Al–O–Si Arrangement of Natural Feldspar Mineral
We
report a facile route to multicomponent complexes of [M{(μ-ddbfo)<sub>2</sub>Al(OSiR<sub>3</sub>)<sub>2</sub>}<sub>2</sub>] (M = Ba, Sr;
ddbfoH = 2,3-dihydro-2,2-dimethylbenzofuran-7-ol; R = Ph, O<sup>t</sup>Bu) as new efficient single-source routes to barium and strontium
celsian feldspar Ba(Sr)Al<sub>2</sub>Si<sub>2</sub>O<sub>8</sub>.
The resulting complexes were characterized by elemental analysis,
IR and NMR spectroscopy, and single-crystal X-ray diffraction. These
compounds calcined at 1100 °C to give porous material Ba(Sr)Al<sub>2</sub>Si<sub>2</sub>O<sub>8</sub>·2SiO<sub>2</sub> as an amorphous
silica matrix containing spherical oxide nanocrystals of celsian feldspar
of ca. 5 nm diameter, as evidenced by transmission and scanning electron
microscopies
Synthesis of Aluminosilicates Containing a Ba(Sr)–O–Al–O–Si Arrangement of Natural Feldspar Mineral
We
report a facile route to multicomponent complexes of [M{(μ-ddbfo)<sub>2</sub>Al(OSiR<sub>3</sub>)<sub>2</sub>}<sub>2</sub>] (M = Ba, Sr;
ddbfoH = 2,3-dihydro-2,2-dimethylbenzofuran-7-ol; R = Ph, O<sup>t</sup>Bu) as new efficient single-source routes to barium and strontium
celsian feldspar Ba(Sr)Al<sub>2</sub>Si<sub>2</sub>O<sub>8</sub>.
The resulting complexes were characterized by elemental analysis,
IR and NMR spectroscopy, and single-crystal X-ray diffraction. These
compounds calcined at 1100 °C to give porous material Ba(Sr)Al<sub>2</sub>Si<sub>2</sub>O<sub>8</sub>·2SiO<sub>2</sub> as an amorphous
silica matrix containing spherical oxide nanocrystals of celsian feldspar
of ca. 5 nm diameter, as evidenced by transmission and scanning electron
microscopies
Impact of Group 13 Metals on Cp<sub>2</sub>TiCl<sub>2</sub> Reduction and Structural Characterization of Resulting Compounds
The aim of the current study was
to examine the effects of group 13 metals on Cp<sub>2</sub>TiCl<sub>2</sub> reduction in the presence of 2-methoxyethanol (MeOEtOH)
or ethanol (EtOH) and the compositions of the resulting products.
Direct reaction of Cp<sub>2</sub>TiCl<sub>2</sub> and M [Al, Al (Fe
contaminated), Ga, In] in toluene/alcohol for 2 h gave a new
family of uncommon homo- and heterometallic compounds: [Cp<sub>2</sub>Ti<sub>2</sub>Al(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>Cl<sub>2</sub>][Ti<sub>2</sub>(μ,η<sup>2</sup>-OEtOMe)<sub>3</sub>(η<sup>2</sup>-OEtOMe)<sub>2</sub>Cl<sub>4</sub>] (<b>1</b>), [Cp<sub>2</sub>Ti<sub>2</sub>Al(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>Cl<sub>2</sub>]Cl (<b>2</b>), [Cp<sub>2</sub>Ti<sub>2</sub>Al(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>Cl<sub>2</sub>][Cp<sub>2</sub>Ti(η<sup>2</sup>-HOEtOMe)][FeCl<sub>4</sub>] (<b>3</b>), [Cp<sub>2</sub>Ti(η<sup>2</sup>-HOEtOMe)][Ga<sub>2</sub>Cl<sub>6</sub>]<sub>0.25</sub>[Cl]<sub>0.5</sub> (<b>4</b>), [Cp<sub>3</sub>Ti<sub>2</sub>(μ-OEt)<sub>2</sub>(OEt)][GaCl<sub>4</sub>] (<b>5</b>), [CpTi(μ,η<sup>2</sup>-OEtOMe)Cl]<sub>2</sub> (<b>6</b>), and
[Cp<sub>3</sub>Ti<sub>2</sub>(μ,η<sup>2</sup>-OEtOMe)(μ-OEtOMe)Cl]
(<b>7</b>). The reaction with indium for 48 h resulted in isolation
of [TiIn<sub>2</sub>(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>(OEtOMe)<sub>2</sub>Cl<sub>4</sub>] (<b>8</b>), [In<sub>2</sub>(μ-OEtOMe)<sub>2</sub>(HOEtOMe)<sub>4</sub>Cl<sub>4</sub>]<sub>2</sub> (<b>9</b>), and [Ti(OEtOMe)<sub>4</sub>] (<b>10</b>). The complexes were characterized using elemental analysis,
IR and NMR spectroscopies, and, for <b>1</b>–<b>9</b>, single-crystal X-ray diffraction. The use of metallic gallium and
indium to reduce Cp<sub>2</sub>TiCl<sub>2</sub> opens up a previously
unexplored path that may provide access to novel and unique compounds
Impact of Group 13 Metals on Cp<sub>2</sub>TiCl<sub>2</sub> Reduction and Structural Characterization of Resulting Compounds
The aim of the current study was
to examine the effects of group 13 metals on Cp<sub>2</sub>TiCl<sub>2</sub> reduction in the presence of 2-methoxyethanol (MeOEtOH)
or ethanol (EtOH) and the compositions of the resulting products.
Direct reaction of Cp<sub>2</sub>TiCl<sub>2</sub> and M [Al, Al (Fe
contaminated), Ga, In] in toluene/alcohol for 2 h gave a new
family of uncommon homo- and heterometallic compounds: [Cp<sub>2</sub>Ti<sub>2</sub>Al(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>Cl<sub>2</sub>][Ti<sub>2</sub>(μ,η<sup>2</sup>-OEtOMe)<sub>3</sub>(η<sup>2</sup>-OEtOMe)<sub>2</sub>Cl<sub>4</sub>] (<b>1</b>), [Cp<sub>2</sub>Ti<sub>2</sub>Al(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>Cl<sub>2</sub>]Cl (<b>2</b>), [Cp<sub>2</sub>Ti<sub>2</sub>Al(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>Cl<sub>2</sub>][Cp<sub>2</sub>Ti(η<sup>2</sup>-HOEtOMe)][FeCl<sub>4</sub>] (<b>3</b>), [Cp<sub>2</sub>Ti(η<sup>2</sup>-HOEtOMe)][Ga<sub>2</sub>Cl<sub>6</sub>]<sub>0.25</sub>[Cl]<sub>0.5</sub> (<b>4</b>), [Cp<sub>3</sub>Ti<sub>2</sub>(μ-OEt)<sub>2</sub>(OEt)][GaCl<sub>4</sub>] (<b>5</b>), [CpTi(μ,η<sup>2</sup>-OEtOMe)Cl]<sub>2</sub> (<b>6</b>), and
[Cp<sub>3</sub>Ti<sub>2</sub>(μ,η<sup>2</sup>-OEtOMe)(μ-OEtOMe)Cl]
(<b>7</b>). The reaction with indium for 48 h resulted in isolation
of [TiIn<sub>2</sub>(μ,η<sup>2</sup>-OEtOMe)<sub>4</sub>(OEtOMe)<sub>2</sub>Cl<sub>4</sub>] (<b>8</b>), [In<sub>2</sub>(μ-OEtOMe)<sub>2</sub>(HOEtOMe)<sub>4</sub>Cl<sub>4</sub>]<sub>2</sub> (<b>9</b>), and [Ti(OEtOMe)<sub>4</sub>] (<b>10</b>). The complexes were characterized using elemental analysis,
IR and NMR spectroscopies, and, for <b>1</b>–<b>9</b>, single-crystal X-ray diffraction. The use of metallic gallium and
indium to reduce Cp<sub>2</sub>TiCl<sub>2</sub> opens up a previously
unexplored path that may provide access to novel and unique compounds
Synthesis and Structural Characterization of Magnesium Drug Complexes: Efficient Initiators for Forming Polylactide–Drug Conjugates
Five novel magnesium alkoxides supported
by drug chelating agents <i>pridinolum</i> (PriOH = 1,1-diphenyl-3-(1-piperidinyl)-1-propanol)
and <i>venlafaxinum</i> (VenlOH = (<i>RS</i>)-1-[2-dimethylamino-1-(4-methoxyphenyl)-ethyl]cyclohexanol)
were successfully synthesized and characterized. Direct reaction of
PriOH and VenlOH with MgBu<sub>2</sub> (1:1) in toluene gives the
dimeric compounds [Mg(μ,η<sup>2</sup>-OPri)<sup><i>n</i></sup>Bu]<sub>2</sub> (<b>1</b>) and [Mg(μ,η<sup>2</sup>-VenlO)<sup><i>n</i></sup>Bu]<sub>2</sub> (<b>2</b>), respectively. Furthermore, the crystallization of an equimolar
mixture of <b>1</b> and <b>2</b> in toluene yields heteroleptic
magnesium complex [Mg(μ,η<sup>2</sup>-OVenl)(η<sup>1</sup>-OPri)]<sub>2</sub> (<b>3</b>). Moreover, reactions
of <b>1</b> and <b>2</b> with 2 molar equivs of the corresponding
drug–ligands give the homoleptic magnesium bis-alkoxides [Mg(μ,η<sup>2</sup>-OPri)(η<sup>1</sup>-OPri)]<sub>2</sub> (<b>4</b>) and [Mg(μ,η<sup>2</sup>-OVenl)(η<sup>1</sup>-OVenl)]<sub>2</sub> (<b>5</b>). The treatment of compound <b>1</b> with 2 equivs of VenlOH or <b>2</b> with 2 equivs of PriOH
leads to the formation of <b>3</b>. Complexes <b>1</b>–<b>5</b> were characterized by elemental analysis,
nuclear magnetic resonance, and single crystal X-ray diffraction (for <b>1</b>–<b>4</b>). It was found that complexes <b>1</b>–<b>5</b> are efficient initiators of the ring-opening
polymerization of l-LA, yielding PLA-OPri and PLA-OVenl conjugates,
respectively. Moreover, the ring-opening polymerization of l-LA initiated by <b>3</b> led to the simultaneous generation
of a blend of poly-l-lactide conjugates with end-capped VenlO
and PriO groups
Synthesis of Functionalized Materials Using Aryloxo-Organometallic Compounds toward Spinel-like MM′<sub>2</sub>O<sub>4</sub> (M = Ba<sup>2+</sup>, Sr<sup>2+</sup>; M′ = In<sup>3+</sup>, Al<sup>3+</sup>) Double Oxides
The predesigned single-source precursors [Ba{(μ-ddbfo)<sub>2</sub>InMe<sub>2</sub>}<sub>2</sub>] (<b>1</b>), [Me<sub>2</sub>In(μ-ddbfo)]<sub>2</sub> (<b>2</b>), [Sr{(μ-ddbfo)<sub>2</sub>AlMe<sub>2</sub>}<sub>2</sub>] (<b>4</b>), and [Me<sub>2</sub>Al(μ-ddbfo)]<sub>2</sub> (<b>5</b>) (ddbfoH =
2,3-dihydro-2,2-dimethylbenzofuran-7-ol) for spinel-like double oxides
and group 13 oxide materials were prepared via the direct reaction
of the homoleptic aryloxide [M(ddbfoH)<sub>4</sub>](ddbfo)<sub>2</sub>·ddbfoH (M = Ba<sup>2+</sup>, Sr<sup>2+</sup> (<b>3</b>)) and InMe<sub>3</sub> or AlMe<sub>3</sub> in toluene. In all of
the reactions, there was an organometallic-driven abstraction of the
OH protons from the 7-benzofuranols in the Ba<sup>2+</sup> and Sr<sup>2+</sup> cation sphere. All compounds were characterized by elemental
analysis, <sup>1</sup>H NMR, and FT-IR spectroscopy. In addition,
the molecular structures of <b>1</b>, <b>2</b>, and <b>3</b> were determined by single-crystal X-ray diffraction. The
oxide products derived from the compounds mentioned above were studied
using elemental analysis, Raman spectroscopy, X-ray powder diffraction,
and scanning and transmission electron microscopy equipped with an
energy-dispersive spectrometer. Moreover, their specific surface area
and mesopore size distribution were evaluated using nitrogen porosimetry.
Preliminary investigations of the Eu-doped SrAl<sub>2</sub>O<sub>4</sub> and In<sub>2</sub>O<sub>3</sub> phosphors revealed that the oxides
obtained could be considered as matrices for lanthanide ions
Synthesis of Functionalized Materials Using Aryloxo-Organometallic Compounds toward Spinel-like MM′<sub>2</sub>O<sub>4</sub> (M = Ba<sup>2+</sup>, Sr<sup>2+</sup>; M′ = In<sup>3+</sup>, Al<sup>3+</sup>) Double Oxides
The predesigned single-source precursors [Ba{(μ-ddbfo)<sub>2</sub>InMe<sub>2</sub>}<sub>2</sub>] (<b>1</b>), [Me<sub>2</sub>In(μ-ddbfo)]<sub>2</sub> (<b>2</b>), [Sr{(μ-ddbfo)<sub>2</sub>AlMe<sub>2</sub>}<sub>2</sub>] (<b>4</b>), and [Me<sub>2</sub>Al(μ-ddbfo)]<sub>2</sub> (<b>5</b>) (ddbfoH =
2,3-dihydro-2,2-dimethylbenzofuran-7-ol) for spinel-like double oxides
and group 13 oxide materials were prepared via the direct reaction
of the homoleptic aryloxide [M(ddbfoH)<sub>4</sub>](ddbfo)<sub>2</sub>·ddbfoH (M = Ba<sup>2+</sup>, Sr<sup>2+</sup> (<b>3</b>)) and InMe<sub>3</sub> or AlMe<sub>3</sub> in toluene. In all of
the reactions, there was an organometallic-driven abstraction of the
OH protons from the 7-benzofuranols in the Ba<sup>2+</sup> and Sr<sup>2+</sup> cation sphere. All compounds were characterized by elemental
analysis, <sup>1</sup>H NMR, and FT-IR spectroscopy. In addition,
the molecular structures of <b>1</b>, <b>2</b>, and <b>3</b> were determined by single-crystal X-ray diffraction. The
oxide products derived from the compounds mentioned above were studied
using elemental analysis, Raman spectroscopy, X-ray powder diffraction,
and scanning and transmission electron microscopy equipped with an
energy-dispersive spectrometer. Moreover, their specific surface area
and mesopore size distribution were evaluated using nitrogen porosimetry.
Preliminary investigations of the Eu-doped SrAl<sub>2</sub>O<sub>4</sub> and In<sub>2</sub>O<sub>3</sub> phosphors revealed that the oxides
obtained could be considered as matrices for lanthanide ions