Tert-butyl Carbazate Research Articles

Tailoring the interface by a multifunctional amphiphilic molecule enabled 24.84%-efficiency and stable perovskite solar cells

Surface defects are detrimental to the performance and stability of perovskite solar cells (PSCs). Herein, an amphiphilic molecule of tert-butyl carbazate (TBC) with multiple functional groups is employed for interface passivation between perovskite and spiro-OMeTAD. We unveil the synergistic mechanism of a) defect-passivation of Pb-related involving coordination and chelation; b) immobilization components through three types of hydrogen bonding interactions; c) enhanced crystallinity and preferential orientation induced by crystal regrowth. These effects minimize the nonradiative recombination and inhibit ion migration. Moreover, TBC introduces a dipole interlayer that facilitates favorable and efficient hole extraction and transport. As a result, the TBC-treated PSCs exhibited a remarkable power conversion efficiency of 24.84%, higher than the control efficiency of 22.04%. Notably, the hydrophobic terminal tert-butyl group confers excellent stability upon the device. Unpackaged devices stored in open-air conditions for 1200 h, experienced only a 5.3% reduction in efficiency. They retained their initial efficiency of 82.7% following 800 h of operation under one-sun illumination in ambient conditions without encapsulation. This proposed interfacial engineering strategy using multiple anchoring groups of amphiphilic molecules presents a new approach for obtaining highly efficient and stable PSCs.

The Continuous-flow Synthesis of 1H-Indazoles via Reaction of o-Fluorobenzaldehydes with tert-Butyl Carbazate under High Teperature

The Continuous-flow Synthesis of 1H-Indazoles via Reaction of o-Fluorobenzaldehydes with tert-Butyl Carbazate under High Teperature

Covalent intercalation of hydrazine derived graphene oxide as an efficient 2D material for supercapacitor application

Herein, we demonstrate a covalent modification of hydrazine functionalized graphene oxide (FGO-H) using a protected tert-butyl carbazate (t-boc) as an intercalating agent over the GO surface and investigated as electrode candidates for electrochemical supercapacitor applications. The resulting functionalized materials were examined by different physicochemical techniques to investigate the physical and structural features of the as-made functionalized GO materials. The favorable method for the surface modification of GO is achieved by treating the primary amine of t-boc with the epoxide groups on the surface of GO. The FGO-TBpa electrode materials lead to the covalent coordinating moieties in between the basal planes of GO by enlargement of interlayer spacing of 1.8 nm from 0.9 nm. More importantly, the functionalized FGO-H can encourage the diffusion of electrolyte ion and result in the enhanced supercapacitance features. Notably, the FGO-H electrode has revealed a comparatively higher specific capacitance of 305 F g−1 at 1 A g−1 and showed excellent capacitance retention of 90%. The functionalized GO-based energy materials will have incredible impending applications in the energy-related systems.

Influence of Oxidation Degree on the Physicochemical Properties of Oxidized Inulin.

This paper reports the oxidation of inulin using varying ratios of sodium periodate and the characterization of the inulin polyaldehyde. The physicochemical properties of the inulin polyaldehyde (oxidized inulin) were characterized using different techniques including 1D NMR spectroscopy, 13C Nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), ultraviolet-visible spectroscopy (UV), and scanning electron microscopy (SEM). The aldehyde peak was not very visible in the FTIR, because the aldehyde functional group exists in a masked form (hemiacetal). The thermal stability of the oxidized inulin decreased with the increasing oxidation degree. The smooth spherical shape of raw inulin was destructed due to the oxidation, as confirmed by the SEM result. The 1HNMR results show some new peaks from 4.8 to 5.0 as well as around 5.63 ppm. However, no aldehyde peak was found around 9.7 ppm. This can be attributed to the hemiacetal. The reaction of oxidized inulin with tert-butyl carbazate produced a carbazone conjugate. There was clear evidence of decreased peak intensity for the proton belonging to the hemiacetal group. This clearly shows that not all of the hemiacetal group can be reverted by carbazate. In conclusion, this work provides vital information as regards changes in the physicochemical properties of the oxidized inulin, which has direct implications when considering the further utilization of this biomaterial.

A Scalable Synthesis of Biaryl Unit of the HIV Protease Inhibitor Atazanavir

Atazanavir is one of the most prescribed HIV-1 protease inhibitors approved by the FDA. It was the first protease inhibitor approved for once-a-day dosing to treat AIDS due to good oral bioavailability and favorable pharmacokinetic profile. This research aims to develop a new synthetic cost effective process for biaryl-hydrazine unit {tert-butyl 2-[4-(2-pyridinyl)benzyl]hydrazinecarboxylate} of atazanavir on a large scale. The synthesis involved palladium catalyzed Suzuki-Miyaura coupling of 2-chloropyridine and (4-cyanophenyl)boronic acid followed by DIBAL-H reduction of cyano group to aldehyde which is then treated with tert-butyl carbazate to furnish hydrazone subsequently in situ reduction with NaBH4. A large scale synthesis of biaryl-hydrazine unit of atazanavir was accomplished in three steps with 71% overall yield. We have developed a short and efficient synthesis of atazanavir key intermediate biaryl-hydrazine unit. The process does not require the usage of Grignard reagent, expensive catalyst, protection/deprotection of aldehyde moiety and catalytic hydrogenation.

Synthesis of 1-aryl-3H-[1,2,5]triazepino[5,4-a]benzimidazol-4(5H)-ones and quantum chemical investigation of the rotamers of the Boc-protected hydrazide key intermediate

3H-[1,2,5]Triazepino[5,4-a]benzimidazol-4(5H)-ones were obtained in five steps involving C-acylation of benzimidazole, its N-alkylation with ethyl bromoacetate, the ester hydrolysis, condensation with BocNHNH2, and the acid-catalyzed heterocyclization of thus obtained 2-(2-aroyl-1H-benzimidazol-1-yl)-N′-(tert-butoxycarbonyl)acetohydrazides. The geometry of tert-butyl carbazate rotamers was estimated with quantum chemical calculations.

Surface charge of well-defined polymeric nano-stars regulates non-invasive fluorescence imaging of lymph node

Accurate identification of sentinel lymph node (SLN) is crucial for clinical SLN biopsy surgery. Herein, we developed an innovative nanoprobe based on well-defined core crosslinked star (CCS) polymers for non-invasive fluorescence imaging of SLN. A well-defined biodegradable CCS polymer comprising multiple polyethylene glycol (PEG) arms and carboxyl terminal groups (denoted as CCS-COOH) was synthesized successfully by reversible addition-fragmentation chain transfer polymerization with a disulfide-based crosslinker reagent. Besides, CCS-COOH was coupled by tert-butyl carbazate to produce the CCS derivative with neutral butoxycarbonyl (Boc) terminal groups (denoted as CCS-Boc). By the removal of Boc groups, another CCS derivative with positive primary amino terminal groups (denoted as CCS-NH2) was also yielded. These CCS polymers had similar particle size but different surface charge. For SLN fluorescence imaging, the CCS polymers labeled by CY7, a near-infrared probe, exhibited superior in vitro photo-stability to CY7 alone. After intradermal injection of the CY7-labeled CCS polymers in a mouse model, they could efficiently accumulate in the lymph node of the mouse. CY7-labeled CCS-COOH having negatively-charged surface displayed longer duration time and higher fluorescence intensity in the lymph node as compared to its counterparts with neutral or positive charge surface. In vitro and in vivo toxicity tests supported low cytotoxicity of these CCS polymers against cell lines and low systemic toxicity. The results of this work highlight the potential of negatively-charged near-infrared-emitting CCS polymer as a new nanoprobe for safe and efficient SLN imaging.

Post-synthetic functionalization of a polysulfone scaffold with hydrazone-linked functionality

The synthesis, characterization, and post-synthetic functionalization of a readily functionalized step-growth linear polymer derived from divinyl sulfone (DVS) and tert-butylcarbazate (TBC) is presented.

Platinum(II) complexes with carbazates and hydrazides: Synthesis, spectral characterization, computational modeling, and biological studies

This work reports on the synthesis and characterization of complexes of the type cis-[Pt(L)2X2], where L=4-methoxybenzylcarbazate (4-MC), benzyl carbazate (BC), 4-fluorophenoxyacetic acid hydrazide (4-FH), 3-methoxybenzoic acid hydrazide (3-MH), ethyl carbazate (EC), tert-butyl carbazate (TC), (4-hydroxy-phenyl)-acetic acid hydrazide (4-HH), and X=Cl− or I−. The structures of the platinum(II) complexes were optimized and theoretical data show good agreement with the experimental results, suggesting that the ligands are coordinated via the NH2 groups. The cytotoxic activity of three representative compounds was evaluated in a chronic myelogenous leukemia cell line and health cell line from mouse (L929). The platinum complex with 4-fluorophenoxyacetic acid hydrazide was more active than the free ligand and carboplatin therefore it may be considered a promising antitumor agent. In addition, the platinum complexes with 4-methoxybenzylcarbazate (4-MC) and benzyl carbazate (BC) exhibited good activity. On the other hand, microbiological assays against Mycobacterium tuberculosis showed that all complexes and organic compounds are not very active.

Spectroscopic characterization and molecular modeling of novel palladium(II) complexes with carbazates and hydrazides

Palladium(II) complexes of the type trans-[Pd(L)2Cl2], where L=4-methoxybenzylcarbazate (4-MC), benzyl carbazate (BC), 4-fluorophenoxyacetic acid hydrazide (4-FH), 3-methoxybenzoic acid hydrazide (3-MH), ethyl carbazate (EC) and tert-butyl carbazate (TC) were synthesized by the slow addition of the ligand to K2PdCl4 previously dissolved in water or ethanol. These complexes were characterized by elemental analyses, conductivity measurements, TG/DTA, FT-IR, mass spectrometric and NMR spectroscopy (solution and solid-state). All coordination compounds exhibit a square planar coordination geometry in which the palladium(II) ion coordinates to two nitrogen atoms and two chlorine atoms. The structures of the palladium(II) complexes were optimized and theoretical data show that the trans isomer is more stable, in accordance with the experimental data. Preliminary in vitro tests of some these new palladium complexes in a chronic myelogenous leukemia cell line (k562 cells) are also reported.

Fluorescence turn-on detection of Sn2+ in live eukaryotic and prokaryotic cells.

Sn(2+) is usually added to toothpaste to prevent dental plaque and oral disease. However, studies of its physiological role and bacteriostatic mechanism are restricted by the lack of versatile Sn(2+) detection methods applicable to live cells, including Streptococcus mutans. Here we report two Sn(2+) fluorescent probes containing a rhodamine B derivative as a fluorophore, linked via the amide moiety to N,N-bis(2-hydroxyethyl)ethylenediamine (R1) and tert-butyl carbazate group (R2), respectively. These probes can selectively chelate Sn(2+) and show marked fluorescence enhancement due to the ring open reaction of rhodamine induced by Sn(2+) chelation. The probes have high sensitivity and selectivity for Sn(2+) in the presence of various relevant metal ions. Particularly, both R1 and R2 can target lysosomes, and R2 can probe Sn concentrations in lysosomes with rather acidic microenvironment. Furthermore, these two probes have low toxicity and can be used as imaging probes for monitoring Sn(2+) not only in live KB cells (eukaryotic) but also in Streptococcus mutans cells (prokaryotic), which is a useful tool to study the physiological function of Sn(2+) in biological systems.

Synthesis of hydrazine and azapeptide derivatives by alkylation of carbazates and semicarbazones

Hydrazine and azapeptide analogs were synthesized effectively by alkylation of alkylidene carbazates and semicarbazones. In comparisons of benzylidene, benzhydrylidene, and fluorenylidene tert-butyl carbazates in alkylations using bases of different pKb character, superior conversion was obtained using the fluorenone derivative. Mild alkylation conditions were found employing Et4NOH as base and used to convert fluorenylidene tert-butyl carbazate into 13 different protected hydrazines. Moreover, racemization was avoided during alkylation of fluorenylidene semicarbazide in the synthesis of aza-propargylglycinylphenylalanine tert-butyl ester, the protecting groups from which could be selectively removed.

Discovery and Process Synthesis of Novel 2,7-Pyrrolo[2,1-f][1,2,4]triazines

The synthesis of a new kinase inhibitor template 2-anilino-7-aryl-pyrrolo[2,1-f][1,2,4]triazine is described which includes a late stage orthogonally reactive key intermediate amenable to rapid diversification as well an optimized in situ triflate displacement to install the C2-aniline. Furthermore, an efficient scalable process approach will be highlighted which begins with tert-butyl carbazate to provide the key N-N bond and generates the pyrrolotriazine core through a stable bromoaldehyde intermediate followed by condensation with ammonium carbonate.

Synthesis of Propargyl-Terminated Heterobifunctional Poly(ethylene glycol)

Novel propargyl-ended heterobifunctional poly(ethylene glycol) (PEG) derivatives with hydroxyl, carboxyl, mercapto or hydrazide end groups were synthesized with simplicity yet high efficiency. PEG (Mw = 3500 Da) with an α-hydroxyl group and an ω-carboxyl was used as the starting polymer. The carboxyl group of the bifunctional PEG was modified into a propargyl, then carboxyl, mercapto or hydrazide groups were introduced to the other end of the bifunctional PEG by modifying the bifunctional PEG’s hydroxyl group with succinic anhydride, cysteamide or tert-butyl carbazate, respectively. This method can be useful to the development of PEG-based bioconjugates for a variety of biomedical applications.

Synthesis and inhibitory activities of novel C-3 substituted azafagomines: A new type of selective inhibitors of α- l-fucosidases

The synthesis of a novel aminomethyl C-3 substituted l- fuco-azafagomine and of its C-6 epimer from d-lyxose is reported. The key step of the synthesis is the introduction of the biimino (–NH–NH–) moiety by reductive hydrazination of a 1-deoxy-ketohexose with tert-butyl carbazate. The 3-aminomethyl-azafagomine derivatives were used as lead compounds in the generation of libraries of novel types of derivatives by attaching different hydrophobic groups on the aminomethyl substituent through amide linkages. These polyhydroxylated hexahydropyridazines can be viewed as a new type of diaza- C-glycoside analogues having a biimino (–NH–NH–) moiety. The conformational analysis and the glycosidase inhibitory properties of all the new C-3 substituted azafagomines synthesized are also reported. Those having l- fuco configuration have shown a selective inhibition of α- l-fucosidases.

Synthesis of Novel 3-Amino(Hydroxy)methyl-l-fuco-Azafagomines as Leads for Selective Inhibitors of α-l-Fucosidases

The synthesis of 3-substituted L- FUCO-azafagomines from D-lyxoseis reported. They represent the first example of aza- C-glycosides having a biimino (-NH-NH-)moiety. The key step of the synthesis is the introduction of thehydrazine moiety by reductive hydrazination of a 1-deoxy-ketohexosewith TERT-butyl carbazate. Their glycosidaseinhibitory properties are also reported.

Tert-Butyl 3-(4-Cyano-5-phenylisothiazol-3-yl)carbazate

3-Iodo-5-phenylisothiazole-4-carbonitrile 1 reacts with tert-butyl carbazate via a Buchwald C-N style coupling to afford tert-butyl 3-(4-cyano-5-phenylisothiazol-3-yl)- carbazate 2 in 70% yield. [...]

The Synthesis, Structure and Reactivity of 1-Thioxotetrahydropyridazino[1,2-a][1,2,4]triazin-4(1H)-one

The synthesis of 1-thioxotetrahydropyridazino[1,2-a][1,2,4]triazin-4-(1H-one 3 in five steps from tert-butyl carbazate and its transformation into 3-benzylidene and 1-amino derivatives are described. Its crystal structure is presented showing it to be an axially chiral molecule that exists as a racemate in the solid state.

Palladium-Catalyzed Cross-Coupling between Vinyl Halides and tert-Butyl Carbazate: First General Synthesis of the Unusual N-Boc-N-alkenylhydrazines

N-Boc-N-alkenylhydrazines, an almost unknown type of compounds, have been prepared with high to moderate yields via palladium-catalyzed cross-coupling between alkenyl halides and tert-butyl carbazate. The present methodology represents the first general way to access this highly functionalized and unusual type of hydrazines. [reaction: see text].

A convenient semicarbazide resin for the solid-phase synthesis of peptide ketones and aldehydes

Use of a semicarbazide resin for the solid-phase preparation of peptide ketones and aldehyde led to optimal results in terms of both purity of the final product and overall yield. This resin was prepared without complication by activation of the commercial available aminomethyl polystyrene with CDI at room temperature, followed by treatment with tert-butyl carbazate. Furthermore, the TNBSA colorimetric assay has been adapted for checking the incorporation of the carbonyl moiety onto hydrazine-based resins.