Tert-butoxy Groups Research Articles

Enhanced Aggregation-Induced Delayed Electrochemiluminescence Triggered by Spatial Perturbation of Organic Dots.

Development of highly efficient, heavy-metal-free electrochemiluminescence (ECL) materials is attractive but still challenging. Herein, we report an aggregation-induced delayed ECL (AIDECL) active organic dot (OD) composed of a tert-butoxy-group-substituted benzophenone-dimethylacridine compound, which shows high ECL efficiency. The resultant ODs exhibit 2.1-fold higher ECL efficiency compared to control AIDECL-active ODs. Molecular stacking combined with theoretical calculations suggests that tert-butoxy groups effectively participate in the intermolecular interactions, further inhibiting the molecular motions in the aggregated states and thus accelerating radiative decay. On the basis of these ODs exhibiting excellent ECL performance, a proof-of-concept biosensor is constructed for the detection of miR-16 associated with Alzheimer's disease, which demonstrates excellent detection ability with the limit of detection of 1.7 fM. This work provides a new approach to improve the ECL efficiency and enriches the fundamental understanding of the structure-property relationship.

Di-tert-butylphosphate Derived Thermolabile Calcium Organophosphates: Precursors for Ca(H2PO4)2, Ca(HPO4), α-/β-Ca(PO3)2, and Nanocrystalline Ca10(PO4)6(OH)2.

Thermally and hydrolytically unstable di-tert-butyl phosphate (dtbp-H) has been used as synthon to prepare discrete and polymeric calcium phosphates that are convenient single-source precursors for a range of calcium phosphate ceramic biomaterials. The reactivity of dtbp-H toward two different calcium sources has been found to vary significantly, e.g., the reaction of Ca(OMe)2 with dtbp-H in a 1:6 molar ratio in petroleum ether forms a mononuclear calcium hexa-phosphate complex [Ca(dtbp)2(dtbp-H)4] (1), whereas the change of calcium source to CaH2, in a 1:2 molar ratio under otherwise similar reaction conditions, yields the calcium phosphate polymer, [Ca(μ-dtbp)2(H2O)2·H2O]n(2). Compounds 1 and 2 have been extensively characterized by various spectroscopic and analytical techniques. The solid-state structures of both 1 and 2 have been determined by single-crystal X-ray diffraction studies. In discrete molecule 1, the central calcium ion is surrounded by two anionic dtbp and four neutral dtbp-H ligands in an octahedral coordination environment. Compound 2 is a one-dimensional polymer in which adjacent calcium ions are connected through double dtbp bridges. Solid-state thermolysis of bulk 1 in air leads to the exclusive formation of calcium metaphosphate β-Ca(PO3)2 in the entire temperature range of 400-800 °C. Thermal decomposition of polymer 2, however, can be fine-tuned to produce either α-Ca(PO3)2 or β-Ca(PO3)2 depending on the thermolysis conditions employed. Although the sample sintered at 600 °C produces exclusively α-form of Ca(PO3)2, the sample annealed at 800 °C or above produces β-form. Both α- and β-forms can also be successively formed one after other by a slow heating of a freshly prepared 2 on the powder diffractometer sample holder. Additional forms of ceramic phosphates have been prepared by solvothermal conditions because of the highly labile nature of the tert-butoxy groups of dtbp in 1 and 2. Solution decomposition of either 1 or 2 in boiling toluene at 140 °C in a sealed tube produces calcium dihydrogen phosphate [Ca(H2PO4)2·H2O] as the only product in the form of single crystals. Solution thermolysis of 2 in protic solvents such as water and methanol can be biased to produce other calcium phosphate biomaterials such as hydroxyapatite [Ca10(PO4)6(OH)2]and calcium monohydrogen phosphate [Ca(HPO4)] in the presence of additional calcium precursors such as CaO and Ca(OMe)2, respectively.

The reaction of (tert-Butoxysilyl)methylmagnesium chlorides with some organotin and organosilicon monochlorides

Interaction between (tert-butoxysilyl)methylmagnesium chlorides of the general formula Me3-n(t-BuO)nSiCH2MgCl, n = 1–3, with some organotin and organosilicon monochlorides has been studied. It has been found that the reaction of the Grignard reagents with trialkyltin chlorides readily proceeds via the methylene carbon with the formation of C-substituted products Me3-n(t-BuO)nSiCH2SnR3, R = Me, n-Bu in high yields. The path of this reaction with Me3SiCl and MePh2SiCl depends on the structure of Grignard compound and chlorosilane electrophilicity. Increasing the number of the tert-butoxy groups in the Grignard reagent has unexpectedly been found to result in the formation of Me3-n(t-BuO)nSiCH2OSiMeR2, R = Me, Ph and decrease of the organosilylmethyl silicon compounds content in the reaction products. The structure of the compounds synthesized has been confirmed by 1H, 13C, 29Si, 117,119Sn NMR spectroscopy and mass spectrometry.

Titanium(IV) complexes supported by a dianionic acenaphthenediimine ligand: X-ray and spectroscopic studies of the metal coordination sphere

The new titanium(IV) coordinative compound (dpp-bian)TiCl2 (2) was obtained by metathesis of the disodium salt (dpp-bian)Na2 (1) (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with TiCl4. It was shown that the chlorido ligands can be exchanged for chelating dpp-bian ligands, or tert-butoxy groups, with the formation of (dpp-bian)2Ti (3) and (dpp-bian)Ti(OtBu)2 (4), respectively. Complexes 2–4 were isolated and fully characterized. It was demonstrated that dpp-bian is in the reduced dianionic form and acts as a σ2π-donor ligand.

Thermolabile Organotitanium Monoalkyl Phosphates: Synthesis, Structures, and Utility as Epoxidation Catalysts and Single-Source Precursors for TiP2O7.

The reaction of [Cp*TiCl3] (Cp* = C5Me5) with monoalkyl phosphates (RO)PO3H2 (R = Me, Et, and iPr) in tetrahydrofuran (THF) at 25 °C leads to the formation of binuclear complexes [Cp*2Ti2(μ-O2P(OH)OR)2(μ-O2P(O)OR)2] [R = Me (1), Et (2), and iPr (3)]. On the other hand, the reaction of ( tBuO)2PO2K with [Cp*TiCl3] in acetonitrile or THF results in isolation of either the dinuclear [Cp*2Ti2(μ-O2P(OH)O tBu)2(μ-O2P(O)O tBu)2] (4) or the trinuclear titanophosphate [Cp*3Ti3(μ-O3PO tBu)2(μ-O)2(μ-O2P(O tBu)2)] (5), respectively. The formation of compounds 4 and 5 is facilitated by partial hydrolysis of the tert-butoxy groups of ( tBuO)2PO2K. New titanophosphates 1-5 have been characterized by spectroscopic and analytical methods, and the molecular structures have further been confirmed by single-crystal X-ray diffraction studies. Thermal decomposition studies of 1-5 reveal the initial loss of thermally labile alkyl substituents of the organophosphate ligands, followed by the loss of C5Me5 groups to form an organic-free amorphous titanophosphate in the temperature range 300-500 °C. This material transforms to highly crystalline titanium pyrophosphate TiP2O7 at 800 °C. Compounds 1-5 and the TiP2O7 materials obtained at 300, 500, and 800 °C through the thermal decomposition of 3 have been employed as efficient homogeneous catalysts for the alkene epoxidation reaction. Using hydrogen peroxide as the oxidant in an acetonitrile medium, these catalysts exhibit >90% alkene conversion with >90% epoxide selectivity in 4 h at temperatures below 100 °C.

C60-containing polymers for electron beam lithography

New C60-containing polymers were synthesized for electron beam lithography. The homo and random copolymers of p-chloromethylstyrene and p-tert-butoxystyrene were produced using a nitroxide-mediated living radical polymerization technique, and then the C60-containing polymers were obtained by the reaction of C60 with the nitroxide-terminated polymers and the subsequent transformation of the tert-butoxy groups to hydroxy groups. The highly sensitive lithographic performance of the resulting electron beam resists led to the fabrication of 50-nm-feature size patterning using the C60-containing copolymers of p-chloromethylstyrene and p-hydroxystyrene.

Rapid atomic layer deposition of silica nanolaminates: synergistic catalysis of Lewis/Brønsted acid sites and interfacial interactions

Rapid atomic layer deposition (RALD) has been applied to prepare various nanolaminates with repeated multilayer structures. The possible reaction pathways for RALD of the Al2O3/SiO2 nanolaminate using trimethylaluminum (TMA) and tris(tert-butoxy)silanol (TBS) are investigated by using density functional theory (DFT) calculations. The introduction of a Lewis-acid catalyst, TMA, can result in the formation of the catalytic site, which accelerates the propagation of the siloxane polymer. The rate-determining step of whole RALD is the elimination of isobutene of the tert-butoxy groups. The Brønsted acid site of [AlO4] can catalyze the elimination of isobutene. At the same time, the interfacial interactions, such as hydrogen bonding interactions between tert-butoxy groups and the surface, further catalyze the elimination of isobutene and accelerate SiO2 RALD reactions. The synergistic catalysis of Lewis/Brønsted acid sites and interfacial interactions may be applied in the RALD fabrication of other silica nanolaminates, such as HfO2/SiO2, ZrO2/SiO2, and TiO2/SiO2, in microelectronics, catalysis, energy storage, and conversion.

New Curable Propylene Copolymers Containing Tert‐Butoxysilane Side Groups

In this work, new, crosslinkable copolymers from propylene and di-tert-butoxy(methyl)(oct-7-enyl)silane are presented. The silane-functionalized monomer is obtained by hydrosilylation of 1,7-octadiene with dichloromethylsilane, followed by the substitution of the chloro atoms by tert-butoxy groups. Homopolymerization and copolymerization with propylene are performed using rac-[ethylenebis(indenyl)]zirconium dichloride. The tert-butoxysilane groups are easily cleaved by acid-catalyzed processes. The resulting copolymer can be completely crosslinked via the tert-butoxysilane functionality to obtain insoluble polymeric material and the gel content of the polymers with different silane content is determined. This method allows control of the copolymer composition and thus of the subsequent extent of crosslinking.

A New Unsymmetrical Zinc Phthalocyanine as Photosensitizers for Dye-sensitized Solar Cells

E-mail: zhangxuejun@nuc.edu.cnReceived July 7, 2011, Accepted January 5, 2012A new unsymmetrical zinc phthalocyanine has been designed and synthesized based on the ‘push-pull’ andextended π-conjugation concept for the dye-sensitized solar cells. Three tert-butoxy groups, which act aselectron releasing (‘push’), enhance the solubility of phthalocyanine in common organic solvents and reducethe aggregation. Hydroxy substituted 9,10-anthraquinones act as electron acceptors (‘pull’) for the study ofphotoinduced electron transfer processes as well as grafting onto nanocrystalline TiO

Syntheses and structures of zinc and tin(II) compounds with hemilabile N-silyl- tert-butylamido and N-silyl- p-tolylamido ligands that contain pendent tert-butoxy groups

Syntheses and solid-state structures of zinc and tin(II) compounds, containing the N-silyl-amide ligands (O t Bu)(NR)SiMe 2, R = t Bu (L t Bu), or R = p-tolyl (L pTol), are reported. The N-silyl amines were synthesized by modified published procedures from commercially available Me 2SiCl 2, t BuOH, and t BuNH 2, or p-Me-C 6H 4NH 2, respectively. Treatment of SnCl 2 with LiL pTol furnished Sn(L pTol) 2, which was X-ray structurally characterized and shown to contain two covalent Sn–N bonds and two asymmetrical O → Sn donor bonds. The single-crystal X-ray structure of Sn(L t Bu) 2 revealed a much more symmetrically-coordinated, pseudo-trigonal-bipyramidal tin atom. Aminolysis of diethylzinc with HL pTol produced [EtZn(L pTol)] 2, which crystallized as a centrosymmetric dimer, containing four-coordinate zinc atoms connected by bridging amides. Zinc dichloride, by contrast, reacted with two equivalents of LiL t Bu to produce the homoleptic, pseudo-spirocyclic Zn(L t Bu) 2.

Synthesis of Fullerene Oxides Containing Both 6,6-Closed Epoxide and 5,6-Open Ether Moieties through Thermolysis of Fullerene Peroxides

Thermolysis of the fullerene hexaadduct C(60)(OO(t)Bu)(6) results in cleavage of two O-O bonds and elimination of two tert-butoxy groups to form two isomeric products with the formula C(60)(O)(2)(OO(t)Bu)(4) in comparable yields. The two oxygen atoms exist as two epoxy groups in one isomer 3, and as an epoxy and an ether group in the other isomer 2. Addition of hydroxylamine to 2 opens both the epoxy and the ether moieties to give a cage-opened keto-ketoxime derivative.

Di-μ-tert-butanolato-bis[bis(η5-cyclopentadienyl) erbium(III)

In the centrosymmetric title compound, [Er2(C5H5)4(C4H9O)2], each Er atom is in a distorted tetrahedral coordination environment, coordinated by two cyclopentadienyl rings and two tert-butoxy groups, forming a dimeric complex bridged through the tert-butoxy groups.

Low-k Interlayer Dielectric Materials: Synthesis and Properties of Alkoxy-Functional Silsesquioxanes

Two new types of silsesquioxanes, (HSiO3/2)x[(tBuO)SiO3/2]z or THQ and (HSiO3/2)x(RSiO3/2)y[(tBuO)SiO3/2]z or THTRQ (R = octadecyl), were synthesized and studied as low-k dielectric materials for electronic applications. The materials were prepared by cohydrolysis and condensation of alkoxy monomers, (AcO)2Si(OtBu)2, HSi(OEt)3, and CH3(CH2)17Si(OMe)3. Spectroscopic data supported retention of tertiary alkoxy groups [(tBuO)SiO3/2 or (tBuO)2SiO2/2] and presence of silanol. The molecular weight of (HSiO3/2)x[(tBuO)SiO3/2]z increased with the T/Q ratio, while that for (HSiO3/2)x(RSiO3/2)y[(tBuO)SiO3/2]z exhibited less dependence on composition. The tert butoxy groups were eliminated in both materials at low temperatures (<450 °C), and subsequent decomposition of octadecyl group (R) in (HSiO3/2)x(RSiO3/2)y[(tBuO)SiO3/2]z occurred through cleavage and re-distribution of carbon−carbon bonds (430−550 °C). Heating at 450 °C for 2 h afforded porous solids. The total pore volume of materials derived from (HSiO3/2)x[...

Characterization of surface NH +3Cl − groups on poly(styrene- co-Boc-aminostyrene) microspheres obtained by controlled acidic treatment

Different samples of aminated latex of poly(styrene- co-Boc-aminostyrene) microspheres with mean diameters varying from 0.7 to 1.0 μm were prepared by dispersion copolymerization of styrene (ST) and Boc-aminostyrene (Boc-AMST). The copolymer compositions determined by nuclear magnetic resonance ( 1H NMR) were Boc-AMST/ST 6.9/93.1 mol/mol % (BOC7 sample) and Boc-AMST/ST 31.3/68.7 mol/mol % (BOC30 sample). The average molecular weights determined by gel permeation chromatography were 126 kDa (BOC7 sample) and 51 kDa (BOC30 sample). The latex containing NH-carbo- tert-butoxy groups (NH-Boc) were treated with 2 M HCl in isopropyl alcohol/water (1:1 vol/vol), at 50 °C for 3, 6, 9, 24, and 30 h, in order to control the extent of deprotection reaction of the NH-Boc. The deprotection reaction resulted in the formation of NH + 3Cl − groups on the particle surfaces. The kinetic of the deprotection reaction was investigated by 1H NMR analyses and the yield varied from 20 to 40%. The resulting NH + 3Cl − groups on the microsphere surfaces were examined, in particular, by electron spectroscopy imaging (ESI) using an energy-filtered transmission electron microscope (EFTEM) that clearly demonstrated the presence of Cl on the particle surfaces. Scanning electron photomicrographs recorded for the above samples showed that the particle morphology was maintained after the acidic treatment.

Formation, crystal and molecular structures of heteroleptic zinc(II) tri- tert-butoxysilanethiolates with ZnNO 2S 2 and ZnN 2S 2 coordination pattern

Five zinc tri- tert-butoxysilanethiolates containing heterocyclic, aromatic bases coordinated to zinc ion were synthesized. All obtained complexes are monomeric with ZnS 2NO 2 or ZnS 2N 2 core and formula: Zn(SSi(OBu t ) 3) 2L, where L is α-picoline (pic), 2,4-lutidine (lut) or N-methylimidazole (meim) or Zn(SSi(OBu t ) 3) 2L 2 where L is pyridine (py) or N-methylimidazole. The complexes are formed in the two-stage synthesis. First zinc acetyloacetonate Zn(acac) 2 reacts with tri- tert-butoxysilanethiol with the formation of [Zn{μ-SSi(OBu t ) 3}(acac)] 2 [B. Becker, A. Dołęga, A. Konitz, W. Wojnowski, Polyhedron 20 (2001) 949]. Subsequent addition of heterocycle leads to decomposition of [Zn{μ-SSi(OBu t ) 3}(acac)] 2 and complexes Zn(SSi(OBu t ) 3) 2L or Zn(SSi(OBu t ) 3) 2L 2 are formed. Crystal structure determinations of the obtained complexes reveal distorted tetrahedral (Zn(SSi(OBu t ) 3) 2L 2) or bipyramidal (Zn(SSi(OBu t ) 3) 2L) coordination of zinc atom. In the case of Zn(SSi(OBu t ) 3) 2L the immediate environment of zinc atom consists of two thiolate sulfur atoms, aromatic nitrogen and two oxygen atoms from tert-butoxy groups of tri- tert-butoxysilanethiolate completing coordination sphere.

Tert‐Butoxysilanols as model compounds for labile key intermediates of the sol–gel process: crystal and molecular structures of (t‐BuO)3SiOH and HO[(t‐BuO)2SiO]2H

AbstractThe tert‐butoxychlorosilanes (t‐BuO)3SiCl (1), (t‐BuO)2SiCl2 (2), and [(t‐BuO)2SiCl]2O (3) were prepared by the reaction of SiCl4 or (Cl3Si)2O with t‐BuOK. Subsequent hydrolysis afforded the tert‐butoxysilanols (t‐BuO)3SiOH (4), (t‐BuO)2Si(OH)2 (5), HO[(t‐BuO)2SiO]2H (6) in high yields. The controlled condensation of 2 and 5 provided HO[(t‐BuO)2SiO]3H (7) in reasonable yields. The tendency of 4–7 to undergo self‐condensation is small, thus enabling their characterization in solution and in the solid state by 29Si NMR spectroscopy, IR spectroscopy and electrospray mass spectrometry, and in the case of 4 and 6 also by X‐ray diffraction. The key feature of the crystal structures is the incorporation of tert‐butoxy groups into the hydrogen bonding. The results obtained are discussed in relation to the sol–gel process. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Self-limiting chemical vapor deposition of an ultra-thin silicon oxide film using tri-( tert-butoxy)silanol

Tri-( tert-butoxy)silanol (tBOS) rapidly forms a self-limited ∼10-Å-thick silicon oxide film upon exposure to a Si(100)-2×1 surface at 300 K. The majority of hydrocarbon spontaneously desorbs at this temperature. Heating to ∼700 K removes the remaining tert-butoxy groups. The films were characterized by conventional X-ray photoelectron spectroscopy (XPS), synchrotron XPS of the Si 2p core-level and valence band regions, and reflection absorption infrared spectroscopy (RAIRS).

Sequential Selective Formation of Adsorbed tert-Butoxy and tert-Butyl Groups from tert-Butyl Formate on Ni(111)

The sequential preparation of tert-butoxy and tert-butyl groups on Ni(111) was achieved through the thermal decomposition of adsorbed tert-butyl formate. The two intermediates were characterized using infrared reflection−absorption spectroscopy, XPS, and TPD measurements. The initial step, below 250 K, yielded coadsorbed tert-butoxy, carbon monoxide, and atomic hydrogen. The second step, in the temperature range 310−370 K, produced adsorbed oxygen atoms and surface tert-butyl groups through scission of the tert-butoxy C−O bond. The complete removal of the tert-butoxy groups coincided with the recombinative desorption of hydrogen adatoms derived from the formyl group of the parent molecule. The decomposition of the tert-butyl groups at 410 K coincided with the desorption limited removal of CO from the surface. Quantitative XPS analysis confirmed that the decomposition of tert-butyl formate on Ni(111) proceeds exclusively through the sequential formation of tert-butoxy and tert-butyl groups.

Alkoxy(siloxy) complexes of tin, lead and bismuth

By reaction of PbCl 2 with 3 equivalents of NaOSi(O tBu) 3 , the ate complex NaPb[OSi(O i Bu) 3] 3 was obtained. This compound possesses a structure containing a 3-coordinate, trigonal prismatic lead center, and a 6-coordinate Na atom encapsulated in an oxygen matrix formed by the bridging siloxy and tert-butoxy groups of the -OSi(O t Bu) 3 ligands. The neutral lead complex Pb[OSi(O t Bu) 3] 2· t BuOH·CH 3CN was obtained from reaction of Pb 3(μ-O t Bu) 6 with HOSi(O t Bu) 3. The tin complex KSn[OSi(O t Bu) 3] 3, prepared from SnCl 2 and KOSi(O t Bu) 3, is isomorphous with NaPb[OSi(O t Bu) 3] 3. The bismuth compounds Bi[OSi(O t Bu) 3] 3 and Bi[OSi(O t Bu) 2Ph] 3 were obtained by similar methods.

Reactivity of a Cyclopentadienyl Containing Heterobimetallic Alkoxide

The synthesis of the new heteroleptic heterotrimetallic cluster, [(C5H5)Sn(μ-OBut)2Ge(OBut)Mo(CO)5] (1) has been achieved by a thermally induced CO substitution of the transition metal derivative, Mo(CO)6, by the basic germanium atom of the cyclopentadienyl heterobimetallic alkoxide, [(C5H5)Sn(μ-OBut)2Ge(OBut)]. The microanalysis, molecular weight (monomer in benzene), IR and multinuclear NMR data and X-ray diffraction study is consistent with the formulation of 1. The Sn atom has a trigonal pyramidal coordination environment formed by a aysmmterically π-bonded terminal C5H5 ring and two symmetrically bridged tert-butoxy groups. The four-coordinate Ge atom lies at the centre of a distorted tetrahedron and is terminally attached to a tert-butoxy group and a Mo(CO)55− fragment.