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Li-Qiang Han, Xia Yuan, Xing-Yu Wu, Ri-Dong Li, Bo Xu, Qing Cheng, Zhen-Ming Liu, Tian-Yan Zhou, Hao-Yun An, Xin Wang, Tie-Ming Cheng, Ze-Mei Ge, Jing-Rong Cui, Run-Tao Li
A novel class of urea-containing peptide boronic acids as proteasome inhibitors was designed by introducing a urea scaffold to replace an amido bond. Compounds were synthesized and their antitumor activities were evaluated. After two rounds of optimizations, the compound I-14 was found to be a potent proteasome inhibitor. Compared with Bortezomib, I-14 showed higher potency against the chymotrypsin-like activity of human 20S proteasome (IC50 < 1 pM), similar potency against four different cancer cell lines (IC50 < 10 nM), and better pharmacokinetic profile...
October 14, 2016: European Journal of Medicinal Chemistry
Jiancheng Zhu, Monica F Enamorado, Daniel L Comins
The syntheses of seven novel amido nicotine derivatives 12-18 from (S)-nicotine are presented. (S)-Nicotine and (S)-6-chloronicotine derivatives were cross-coupled with the corresponding amides 6-10 at the C-4 position of the pyridine ring via copper (I)-mediated reactions. Derivatives 16-18 were also obtained via copper (II)-mediated reactions from (S)-nicotine containing a C-4 boronic acid pinacol ester group. The optimization of reaction conditions for both routes provided useful procedures for preparing C-4 amide-containing nicotine analogs...
October 21, 2016: Journal of Organic Chemistry
Jorge A Gonzalez, O Maduka Ogba, Gregory F Morehouse, Nicholas Rosson, Kendall N Houk, Andrew G Leach, Paul H-Y Cheong, Martin D Burke, Guy C Lloyd-Jones
MIDA boronates (N-methylimidodiacetic boronic acid esters) serve as an increasingly general platform for small-molecule construction based on building blocks, largely because of the dramatic and general rate differences with which they are hydrolysed under various basic conditions. Yet the mechanistic underpinnings of these rate differences have remained unclear, which has hindered efforts to address the current limitations of this chemistry. Here we show that there are two distinct mechanisms for this hydrolysis: one is base mediated and the other neutral...
November 2016: Nature Chemistry
S Drijkoningen, S D Janssens, P Pobedinskas, S Koizumi, M K Van Bael, K Haenen
Nanocrystalline diamond (NCD) membranes are promising candidates for use as sensitive pressure sensors. NCD membranes are able to withstand harsh conditions and are easily fabricated on glass. In this study the sensitivity of heavily boron doped NCD (B:NCD) pressure sensors is evaluated with respect to different types of supporting glass substrates, doping levels and membrane sizes. Higher pressure sensing sensitivities are obtained for membranes on Corning Eagle 2000 glass, which have a better match in thermal expansion coefficient with diamond compared to those on Schott AF45 glass...
October 21, 2016: Scientific Reports
Jin Li, Qian Zhang, Jian Yin, Changjiang Yu, Kai Cheng, Yun Wei, Erhong Hao, Lijuan Jiao
Prodiginines, as a family of bacterial alkaloids, possess a number of interesting biological activities. New, concise synthetic routes for the facile preparation of both synthetic and natural prodiginines in good yields have been developed, which use BODIPY functionalization reactions, such as condensation, nucleophilic substitution, and BF2 deprotection. This new metal-free synthetic method opens the door toward a wide variety of C-ring functionalized prodiginines, including those that are not possible to obtain through current synthetic methods, for their advanced biological activities...
October 21, 2016: Organic Letters
Joana Roßberg, Falko O Rottke, Burkhard Schulz, Andreas Lendlein
The influence of terminal functionalization of oligo(ε-caprolactone)s (OCL) with phenylboronic acid pinacol ester or phenylboronic acid on the enzymatic degradation behavior at the air-water interface is investigated by the Langmuir monolayer degradation technique. While the unsubstituted OCL immediately degrades after injection of the enzyme lipase from Pseudomonas cepacia, enzyme molecules are incorporated into the films based on end-capped OCL before degradation. This incorporation of enzymes does not inhibit or suppress the film degradation, but retards it significantly...
October 20, 2016: Macromolecular Rapid Communications
Matthew Yankowitz, K Watanabe, T Taniguchi, Pablo San-Jose, Brian J LeRoy
Combining atomically-thin van der Waals materials into heterostructures provides a powerful path towards the creation of designer electronic devices. The interaction strength between neighbouring layers, most easily controlled through their interlayer separation, can have significant influence on the electronic properties of these composite materials. Here, we demonstrate unprecedented control over interlayer interactions by locally modifying the interlayer separation between graphene and boron nitride, which we achieve by applying pressure with a scanning tunnelling microscopy tip...
October 20, 2016: Nature Communications
Mayuki Tanaka, Naoyuki Sotta, Yusuke Yamazumi, Yui Yamashita, Kyoko Miwa, Katsunori Murota, Yukako Chiba, Masami Yokota Hirai, Tetsu Akiyama, Hitoshi Onouchi, Satoshi Naito, Toru Fujiwara
Upstream open reading frames (uORFs) are often translated ahead of the main ORF of a gene and regulate gene expression, sometimes in a condition-dependent manner, but such a role for the minimum uORF (hereafter referred to as 'AUG-stop') in living organisms is currently unclear. Here, we show that AUG-stop plays an important role in the boron (B)-dependent regulation of NIP5;1, encoding a boric acid channel required for normal growth under low B conditions in Arabidopsis thaliana. High B enhanced ribosome stalling at AUG-stop, which was accompanied by the suppression of translation and mRNA degradation...
October 19, 2016: Plant Cell
Mouritz N Svenson, Randall E Youngman, Yuanzheng Yue, Sylwester J Rzoska, Michal Bockowski, Lars R Jensen, Morten M Smedskjaer
The structure and properties of glass can be modified through compression near the glass transition temperature (Tg), and such modified structure and properties can be maintained at ambient temperature and pressure. However, once the compressed glass undergoes annealing near Tg at ambient pressure, the modified structure and properties will relax. The challenging question is how the property relaxation is correlated with both the local and the medium-range structural relaxation. In this paper, we answer this question by studying the volume (density) and structural relaxation of a sodium borate glass that has first been pressure-quenched from its Tg at 1 GPa, and then annealed at ambient pressure under different temperature-time conditions...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Bikramjeet Singh, Gurpreet Kaur, Paviter Singh, Kulwinder Singh, Baban Kumar, Ankush Vij, Manjeet Kumar, Rajni Bala, Ramovatar Meena, Ajay Singh, Anup Thakur, Akshay Kumar
Highly water dispersible boron based compounds are innovative and advanced materials which can be used in Boron Neutron Capture Therapy for cancer treatment (BNCT). Present study deals with the synthesis of highly water dispersible nanostructured Boron Nitride (BN). Unique and relatively low temperature synthesis route is the soul of present study. The morphological examinations (Scanning/transmission electron microscopy) of synthesized nanostructures showed that they are in transient phase from two dimensional hexagonal sheets to nanotubes...
October 19, 2016: Scientific Reports
Kayako Isohashi, Eku Shimosegawa, Sadahiro Naka, Yasukazu Kanai, Genki Horitsugi, Ikuko Mochida, Keiko Matsunaga, Tadashi Watabe, Hiroki Kato, Mitsuaki Tatsumi, Jun Hatazawa
BACKGROUND: In boron neutron capture therapy (BNCT), positron emission tomography (PET) with 4-borono-2-(18)F-fluoro-phenylalanine (FBPA) is the only method to estimate an accumulation of (10)B to target tumor and surrounding normal tissue after administering (10)B carrier of L-paraboronophenylalanine and to search the indication of BNCT for individual patient. Absolute concentration of (10)B in tumor has been estimated by multiplying (10)B concentration in blood during BNCT by tumor to blood radioactivity (T/B) ratio derived from FBPA PET...
December 2016: EJNMMI Research
Chenping Wu, Abdul Majid Soomro, Feipeng Sun, Huachun Wang, Youyang Huang, Jiejun Wu, Chuan Liu, Xiaodong Yang, Na Gao, Xiaohong Chen, Junyong Kang, Duanjun Cai
Hexagonal boron nitride (h-BN) is known as promising 2D material with a wide band-gap (~6 eV). However, the growth size of h-BN film is strongly limited by the size of reaction chamber. Here, we demonstrate the large-roll synthesis of monolayer and controllable sub-monolayer h-BN film on wound Cu foil by low pressure chemical vapor deposition (LPCVD) method. By winding the Cu foil substrate into mainspring shape supported by a multi-prong quartz fork, the reactor size limit could be overcome by extending the substrate area to a continuous 2D curl of plane inward...
October 19, 2016: Scientific Reports
Masaaki Mitsui, Koji Higashi, Yohei Hirumi, Kenji Kobayashi
The effects of supramolecular encapsulation on the photophysics and photostability of a highly fluorescent dimeric derivative of 2,6-diacetoxy-9,10-bis(arylethynyl)anthracene (G2) were investigated by single-molecule fluorescence spectroscopy (SMFS). The fluorescence properties of free-G2 and its self-assembled boronic ester encapsulation complex, G2@(Cap)2, were compared in solution and a glassy polymer film. The fluorescence spectral characteristics and theoretical calculations suggest that the environment affects the excited-state conformation and subsequent fluorescence emission of G2@(Cap)2...
October 18, 2016: Journal of Physical Chemistry. A
Jeanne Crassous, Chengshuo Shen, Monika Srebro-Hooper, Marion Jean, Nicolas Vanthuyne, Gilles Muller, Loïc Toupet, J A Gareth Williams, Jochen Autschbach, Alexis Torres, Adrian Riives
Four members of a new class of cycloborylated hexa- to deca-helicenes (1a-d) have been prepared in enantiopure forms, along with cycloplatinated deca-helicenes (1d', 1d1) further extending a family of cycloplatinated hexa- to octa-helicenes reported previously. The azabora[n]helicenes display intense electronic circular dichroism and strong optical rotations, whose dependence on the size of the helix (n = 6, 8, or 10) and number of boron atoms (1 or 2) has been examined in detail both experimentally and theoretically...
October 18, 2016: Chemistry: a European Journal
Boran Lee, Byung Gyu Park, Wansang Cho, Ho Yong Lee, András Olasz, Chun-Hsing Chen, Seung Bum Park, Dongwhan Lee
A series of air-stable boron complexes 1-5 were prepared by using N-aryl iminopyrrolide ligands. Designed as minimalist structural mimics of the privileged BODIPY motif, these new BOIMPY (BOron complexes of IMinoPYrrolide ligands) fluorophores feature low molecular symmetry that promotes emission from CT-type excited states with large Stokes shifts and little self-quenching. Through comparative studies on the homologous set of compounds 1-4, we have confirmed that a delicate interplay between conformational twisting and donor-acceptor interaction dictates the mechanism of de-excitation, which responds sensitively to solvent polarity as well as protonation states...
October 18, 2016: Chemistry: a European Journal
Dennis G Hall, Taras Rybak, Tristan Verdelet
Multicomponent reactions (MCR), transformations employing three or more simple substrates in a single and highly atom-economical operation, are very attractive in both natural product synthesis and diversity-oriented synthesis of druglike molecules. Several popular multicomponent reactions were designed by combining two well-established individual reactions that utilize mutually compatible substrates. In this regard, it is not surprising that the merging of two reactions deemed as workhorses of stereoselective synthesis, the Diels-Alder cycloaddition and carbonyl allylboration, would produce a powerful and highly versatile tandem MCR process...
October 18, 2016: Accounts of Chemical Research
Hui Bai, Bing Bai, Lin Zhang, Wei Huang, Yue-Wen Mu, Hua-Jin Zhai, Si-Dian Li
The recent discovery of borospherene B40 marks the onset of a new kind of boron-based nanostructures akin to the C60 buckyball, offering opportunities to explore materials applications of nanoboron. Here we report on the feasibility of Li-decorated B40 for hydrogen storage using the DFT calculations. The B40 cluster has an overall shape of cube-like cage with six hexagonal and heptagonal holes and eight close-packing B6 triangles. Our computational data show that Lim&B40(1-3) complexes bound up to three H2 molecules per Li site with an adsorption energy (AE) of 0...
October 18, 2016: Scientific Reports
Mohsen Golabi, Filiz Kuralay, Edwin W H Jager, Valerio Beni, Anthony P F Turner
Biosensors can deliver the rapid bacterial detection that is needed in many fields including food safety, clinical diagnostics, biosafety and biosecurity. Whole-cell imprinted polymers have the potential to be applied as recognition elements in biosensors for selective bacterial detection. In this paper, we report on the use of 3-aminophenylboronic acid (3-APBA) for the electrochemical fabrication of a cell-imprinted polymer (CIP). The use of a monomer bearing a boronic acid group, with its ability to specifically interact with cis-diol, allowed the formation of a polymeric network presenting both morphological and chemical recognition abilities...
September 26, 2016: Biosensors & Bioelectronics
Maximiliano L Agazzi, M Belén Ballatore, Eugenia Reynoso, Ezequiel D Quiroga, Edgardo N Durantini
Two cationic BODIPYs 3 and 4 were synthesized by acid-catalyzed condensation of the corresponding pyrrole and benzaldehyde, followed by complexation with boron and methylation. Compound 3 contains methyl at the 1,3,5 and 7 positions of the s-indacene ring and a N,N,N-trimethylamino group attached to the phenylene unit, while 4 is not substituted by methyl groups and the cationic group is bound by an aliphatic spacer. UV-visible absorption spectra of these BODIPYs show an intense band at ∼500 nm in solvents of different polarities and n-heptane/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water reverse micelles...
October 3, 2016: European Journal of Medicinal Chemistry
Bofeng Zhu, Guobin Ren, Beilei Wu, Yixiao Gao, Haisu Li, Shuisheng Jian
In this Letter, we investigate the nanofocusing of hybrid plasmons-phonons-polaritons (SPP-HPhPs) in a graphene-hexagonal boron nitride (h-BN) heterostructure with a graphene coating on a tapered h-BN slab. Compared with the hyperbolic phonon polariton (HPhP) in h-BN, the hybrid SPP-HPhP in a heterostructure exhibits much smaller losses, which is validated through both analytical and numerical methods. Furthermore, the thickness dependent dispersions of a hybrid SPP-HPhP enable the tapered heterostructure to achieve a function of focusing electromagnetic waves...
October 1, 2016: Optics Letters
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