30 research outputs found
Fluphenazine dihydrochloride dimethanol solvate
In the title compound {systematic name: 1-(2-hydroxyethyl)-4-[3-(2-trifluoromethyl-10H-phenothiazin-10-yl)propyl]piperazine-1,4-diium dichloride dimethanol disolvate}, C22H28F3N3OS2+·2Cl−·2CH3OH, the dihedral angle between the planes of the two outer benzene rings of the tricyclic phenothiazine system is 46.91 (13)°. The piperazine ring adopts a chair conformation. The crystal structure is stabilized by O—H⋯Cl, N—H⋯Cl, C—H⋯O, C—H⋯Cl and C—H⋯F hydrogen bonds and contacts
Structure and reactivity of alkoxy-zinc compounds as initiators/catalysts in the polymerization of cyclic esters
This review focuses on advances in the synthesis and structural chemistry of zinc alkoxide compounds for use in the catalytic ring-opening polymerization (ROP) of lactides (LAs). This route was used for the preparation of lactic acid based polymers - referred to as polylactides (PLAs). These polyesters have ecofriendly properties such as renewability, biocompatibility, and biodegradability, and are therefore among the most promising green polymers. PLAs have found numerous specialty applications in the biomedical industry, such as biodegradable screws and sutures, scaffolds for tissue engineering, matrices for controlled drug delivery systems, and environmentally friendly food-packaging materials. In industry, PLAs were synthesized by bulk polymerization of LA using tin(II) alkoxides synthesized in situ from tin(II) 2-ethylhexanoate. The toxicity associated with most tin compounds is a considerable drawback in the case of biomedical applications. There has therefore been much research devoted to finding well- defined complexes of high activity containing biologically benign metals. In this context, zinc alkoxides are very attractive non-toxic initiators for the synthesis of polymers that could be used in medical and environmental fields. The most broadly applied representations of zinc initiators for ROP of LA are zinc carboxylates, ß-diketonates, ß-diketiminates, phenolates and bisphenolates, trispyrazolyl- and trisindazolyl-borates, heteroscorpionates, aminophenolates, Schiff base, and iminealkoxylates. The mentioned above initiators were classified and analyzed in the context of their coordination chemistry and revealed catalytic activity in the ROP of LA. The review contains only pioneering/groundbreaking works that allowed for setting new research paths for each of the described groups of initiators, showing how this theme has changed over the last several decades
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
Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba2+, Sr2+, Ca2+) Derived from Molecular Precursors and Doped with Eu3+ Ions
The effect of alkaline earth metal alkoxides on the protonation of zirconocene dichloride was investigated. This approach enabled the design of compounds with preset molecular structures for generating highâ purity binary metal oxide perovskites MZrO3 (M=Ba2+, Sr2+, Ca2+). Singleâ source molecular precursors [Ba4Zr2(μ6â O)(μ3,η2â OR)8(OR)2(η2â HOR)2(HOR)2Cl4], [Sr4Zr2(μ6â O)(μ3,η2â OR)8(OR)2(HOR)4Cl4], [Ca4Zr2(μ6â O)(μ3,η2â OR)8(OR)2Cl4], and [Ca6Zr2(μ2,η2â OR)12(μâ Cl)2(η2â HOR)4Cl6]â 8â CH2Cl2 were prepared via elimination of the cyclopentadienyl ring from Cp2ZrCl2 as CpH in the presence of M(OR)2 and alcohol ROH (ROH=CH3OCH2CH2OH) as a source of protons. The resulting complexes were characterized by elemental analysis, IR and NMR spectroscopy, and singleâ crystal Xâ ray diffraction. The compounds were then thermally decomposed to MCl2/MZrO3 mixtures. Leaching of MCl2 from the raw powder with deionized water produced highly pure perovskiteâ like oxide particles of 40â 80â nm in size. Luminescence studies on Eu3+â doped MZrO3 revealed that the perovskites are attractive host lattices for potential applications in display technology.Molecular perovskite precursors: A simple, highâ yield synthetic route for the preparation of singleâ source molecular precursors for preparing alkaline earth metal zirconate perovskites MZrO3 (M=Ba, Sr, and Ca; see figure), which were subsequently doped with Eu3+ ions, is presented. The CaZrO3:Eu3+ phosphor showed the highest luminescent intensity and is a highly promising candidate for applications in trichromatic white LEDs.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137272/1/chem201504846-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137272/2/chem201504846_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137272/3/chem201504846.pd