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Chemical Science

Tom Podewin, Johannes Broichhagen, Christina Frost, Dieter Groneberg, Julia Ast, Helena Meyer-Berg, Nicholas H F Fine, Andreas Friebe, Martin Zacharias, David J Hodson, Dirk Trauner, Anja Hoffmann-Röder
The optical control over biological function with small photoswitchable molecules has gathered significant attention in the last decade. Herein, we describe the design and synthesis of a small library of photoswitchable peptidomimetics based upon human atrial natriuretic peptide (ANP), in which the photochromic amino acid [3-(3-aminomethyl)phenylazo]phenylacetic acid (AMPP) is incorporated into the peptide backbone. The endogeneous hormone ANP signals via the natriuretic peptide receptor A (NPR-A) through raising intracellular cGMP concentrations, and is involved in blood pressure regulation and sodium homeostasis, as well as lipid metabolism and pancreatic function...
June 1, 2017: Chemical Science
Yuchuan Wang, Ligang Hu, Feng Xu, Quan Quan, Yau-Tsz Lai, Wei Xia, Ya Yang, Yuen-Yan Chang, Xinming Yang, Zhifang Chai, Junwen Wang, Ivan K Chu, Hongyan Li, Hongzhe Sun
Bismuth drugs, despite being clinically used for decades, surprisingly remain in use and effective for the treatment of Helicobacter pylori infection, even for resistant strains when co-administrated with antibiotics. However, the molecular mechanisms underlying the clinically sustained susceptibility of H. pylori to bismuth drugs remain elusive. Herein, we report that integration of in-house metalloproteomics and quantitative proteomics allows comprehensive uncovering of the bismuth-associated proteomes, including 63 bismuth-binding and 119 bismuth-regulated proteins from Helicobacter pylori, with over 60% being annotated with catalytic functions...
June 1, 2017: Chemical Science
Silvia Alonso-de Castro, Emmanuel Ruggiero, Ane Ruiz-de-Angulo, Elixabete Rezabal, Juan C Mareque-Rivas, Xabier Lopez, Fernando López-Gallego, Luca Salassa
Encouraging developments demonstrate that few transition metal and organometallic catalysts can operate in a bioorthogonal fashion and promote non-natural chemistry in living systems by minimizing undesired side reactions with cellular components. These catalytic processes have potential for applications in medicinal chemistry and chemical biology. However, the stringent conditions of the cell environment severely limit the number of accessible metal catalysts and exogenous reactions. Herein, we report an unorthodox approach and a new type of bioorthogonal catalytic reaction, in which a metal complex is an unconventional substrate and an exogenous biological molecule acts as a catalyst...
June 1, 2017: Chemical Science
Zhongwei Hu, Lasse Jensen
The two-photon absorption (TPA) cross-sections of small thiolate-protected gold clusters have been shown to be much larger than typical small organic molecules. In comparison with larger nanoparticles, their TPA cross-sections per gold atom are also found to be larger. Theoretical simulations have suggested that the large enhancement of these TPA cross-sections comes from a one-photon double-resonance mechanism. However, it remains difficult to simulate TPA cross-sections of thiolate-protected gold clusters due to their large system size and a high density of states...
June 1, 2017: Chemical Science
Yong Cheng, Chunli Sun, Xiaowen Ou, Bifeng Liu, Xiaoding Lou, Fan Xia
Precisely targeted transportation of a long-term tracing regent to a nucleus with low toxicity is one of the most challenging concerns in revealing cancer cell behaviors. Here, we report a dual-targeted peptide-conjugated multifunctional fluorescent probe (cNGR-CPP-NLS-RGD-PyTPE, TCNTP) with aggregation-induced emission (AIE) characteristic, for efficient nucleus-specific imaging and long-term and low-toxicity tracing of cancer cells. TCNTP mainly consists of two components: one is a functionalized combinatorial peptide (TCNT) containing two targeted peptides (cNGR and RGD), a cell-penetrating peptide (CPP) and a nuclear localization signal (NLS), which can specifically bind to a cell surface and effectively enter into the nucleus; the other one is an AIE-active tetraphenylethene derivative (PyTPE, a typical AIEgen) as fluorescence imaging reagent...
June 1, 2017: Chemical Science
Azhar Mahmood, Nanhong Xie, Muhammad Aizaz Ud Din, Faisal Saleem, Haifeng Lin, Xun Wang
Mechanistic control is a powerful means for manufacturing specific shapes of metal nanostructures and optimizing their performance in a variety of applications. Thus, we successfully synthesized multimetallic nanoplates (PtAgBiCo and PtAgBi) by combining the concepts of crystal symmetry, oxidative etching and seed ratio, and tuned their activity, stability and methanol tolerance, as well as Pt utilization, for the oxygen reduction reaction in direct methanol fuel cells. Systematic studies reveal that the formation of PtAgBiCo triangular nanoplates with a high morphological yield (>90%) can be achieved by crystallinity alteration, while electrochemical measurements indicate that the PtAgBiCo nanoplates have superior electrocatalytic activity towards the oxygen reduction reaction...
June 1, 2017: Chemical Science
Wen Liu, Yingying Mi, Zhe Weng, Yiren Zhong, Zishan Wu, Hailiang Wang
Dendrite growth and low coulombic efficiency are two major factors that limit the utilization of Li metal electrodes in future generations of high-energy-density rechargeable batteries. This article reports the first study on metal-organic framework (MOF) materials for boosting the electrochemical performance of Li metal electrodes and demonstrates the power of molecular-structure functionalization for realizing desirable ion transport and Li metal nucleation and growth. We show that dendrite-free dense Li deposition and stable Li plating/stripping cycling with high coulombic efficiency are enabled by modifying a commercial polypropylene separator with a titanium-based MOF (NH2-MIL-125(Ti)) material...
June 1, 2017: Chemical Science
Babu Sudhamalla, Debasis Dey, Megan Breski, Tiffany Nguyen, Kabirul Islam
Chemical modifications on DNA, RNA and histones are recognized by an array of 'reader' modules to regulate transcriptional programming and cell fate. However, identification of reader-specific interacting partners in a dynamic cellular environment remains a significant challenge. Herein, we report a chemoproteomic approach termed 'interaction-based protein profiling' (IBPP) to characterize novel interacting partners of potentially any reader protein. IBPP harnesses a photosensitive amino acid introduced into the hydrophobic pocket of a reader module to crosslink and enrich transient interacting partners that are inaccessible to traditional methods...
June 1, 2017: Chemical Science
Ru-Ru Gao, Tian-Ming Yao, Xiao-Yan Lv, Yan-Yan Zhu, Yi-Wei Zhang, Shuo Shi
To create sophisticated molecular logic circuits from scratch, you may not believe how common the building blocks can be and how diverse and powerful such circuits can be when scaled up. Using the two simple building blocks of G-quadruplex and silver nanoclusters (Ag NCs), we experimentally construct a series of multifunctional, label-free, and multi-output logic circuits to perform nonarithmetic functions: a 1-to-2 decoder, a 4-to-2 encoder, an 8-to-3 encoder, dual transfer gates, a 2 : 1 multiplexer, and a 1 : 2 demultiplexer...
June 1, 2017: Chemical Science
Chen Bai, Seyit Kale, Judith Herzfeld
For a century now, "Lewis dots" have been a mainstay of chemical thinking, teaching and communication. However, chemists have assumed that this semi-classical picture of electrons needs to be abandoned for quantitative work, and the recourse in computational simulations has been to the extremes of first principles treatments of electrons on the one hand and force fields that avoid explicit electrons on the other hand. Given both the successes and limitations of these highly divergent approaches, it seems worth considering whether the Lewis dot picture might be made quantitative after all...
June 1, 2017: Chemical Science
Peter D Matthews, Paul D McNaughter, David J Lewis, Paul O'Brien
Transition metal chalcogenides are an important family of materials that have received significant interest in recent years as they have the potential for diverse applications ranging from use in electronics to industrial lubricants. One of their most exciting properties is the ability to generate electricity from incident light. In this perspective we will summarise and highlight the key results and challenges in this area and explain how transition metal chalcogenides are a good choice for future sustainable photovoltaics...
June 1, 2017: Chemical Science
Lei Sun, Christopher H Hendon, Sarah S Park, Yuri Tulchinsky, Ruomeng Wan, Fang Wang, Aron Walsh, Mircea Dincă
Identifying the metal ions that optimize charge transport and charge density in metal-organic frameworks is critical for systematic improvements in the electrical conductivity in these materials. In this work, we measure the electrical conductivity and activation energy for twenty different MOFs pertaining to four distinct structural families: M2(DOBDC)(DMF)2 (M = Mg(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+)); H4DOBDC = 2,5-dihydroxybenzene-1,4-dicarboxylic acid; DMF = N,N-dimethylformamide), M2(DSBDC)(DMF)2 (M = Mn(2+), Fe(2+); H4DSBDC = 2,5-disulfhydrylbenzene-1,4-dicarboxylic acid), M2Cl2(BTDD)(DMF)2 (M = Mn(2+), Fe(2+), Co(2+), Ni(2+); H2BTDD = bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i]dibenzo[1,4]dioxin), and M(1,2,3-triazolate)2 (M = Mg(2+), Mn(2+), Fe(2+), Co(2+), Cu(2+), Zn(2+), Cd(2+))...
June 1, 2017: Chemical Science
Pablo Ríos, Tiddo J Mooibroek, Tom S Carter, Christopher Williams, Miriam R Wilson, Matthew P Crump, Anthony P Davis
Carbohydrate receptors with a chiral framework have been generated by combining a tetra-aminopyrene and a C3-symmetrical triamine via isophthalamide spacers bearing water-solubilising groups. These "synthetic lectins" are the first to show enantiodiscrimination in aqueous solution, binding N-acetylglucosamine (GlcNAc) with 16 : 1 enantioselectivity. They also show exceptional affinities. GlcNAc is bound with Ka up to 1280 M(-1), more than twice that measured for previous synthetic lectins, and three times the value for wheat germ agglutinin, the lectin traditionally employed to bind GlcNAc in glycobiological research...
May 1, 2017: Chemical Science
Xiaoyan Lin, Aleksandar P Ivanov, Joshua B Edel
Single molecule detection methods, such as nanopore sensors have found increasing importance in applications ranging from gaining a better understanding of biophysical processes to technology driven solutions such as DNA sequencing. However, challenges remain especially in relation to improving selectivity to probe specific targets or to alternatively enable detection of smaller molecules such as small-sized proteins with a sufficiently high signal-to-noise ratio. In this article, we propose a solution to these technological challenges by using DNA aptamer-modified gold nanoparticles (AuNPs) that act as a molecular carrier through the nanopore sensor...
May 1, 2017: Chemical Science
Kelong Zhu, Giorgio Baggi, V Nicholas Vukotic, Stephen J Loeb
The T-shaped benzimidazolium/crown ether recognition motif was used to prepare suit[1]anes. These novel mechanically interlocked molecules (MIMs) were fully characterized by (1)H and (13)C NMR spectroscopy, single-crystal X-ray diffraction, UV-vis absorption and fluorescence spectroscopy. By conversion to a suit[1]ane, a simple benzimidazole was shown to be protected from deprotonation by strong base. Moreover, it was demonstrated that this unique three-dimensional encapsulation can be made reversible, thus introducing the concept of "reversible mechanical protection"; a protecting methodology that may have potential applications in synthetic organic chemistry and the design of molecular machinery...
May 1, 2017: Chemical Science
Yong-Mei Wang, Wei Liu, Xue-Bo Yin
The one-step self-assembly preparation of multifunctional gadolinium (Gd)-ytterbium (Yb) mixed-metal nanoscale coordination polymers (NCPs) with Ru[4,4'-(COOH)2bpy]3(2+) (LRu , bpy = bipyridyl) as a ligand is reported. The Gd/Yb ratio in the NCPs is easily tuned by their ratio in the precursors while the self-limiting growth is realized with the high coordination valence and rigid steric structure of the precursors. The inherent properties of the precursors, including the magnetic resonance (MR) response of Gd(3+), the X-ray attenuation properties of Yb(3+), and the red fluorescence and the singlet-oxygen generation of LRu , are well retained in the mixed-metal NCPs...
May 1, 2017: Chemical Science
Gayathri Devatha, Soumendu Roy, Anish Rao, Abhik Mallick, Sudipta Basu, Pramod P Pillai
Indium Phosphide Quantum Dots (InP QDs) have emerged as an alternative to toxic metal ion based QDs in nanobiotechnology. The ability to generate cationic surface charge, without compromising stability and biocompatibility, is essential in realizing the full potential of InP QDs in biological applications. We have addressed this challenge by developing a place exchange protocol for the preparation of cationic InP/ZnS QDs. The quaternary ammonium group provides the much required permanent positive charge and stability to InP/ZnS QDs in biofluids...
May 1, 2017: Chemical Science
Zhong-Fu Pang, Tian-You Zhou, Rong-Ran Liang, Qiao-Yan Qi, Xin Zhao
The topology of a covalent organic framework (COF) is generally believed to be dictated by the symmetries of the monomers used for the condensation reaction. In this context, the use of monomers with different symmetries is usually required to afford COFs with different topologies. Herein, we report a conceptual strategy to regulate the topology of 2D COFs by introducing alkyl substituents into the skeleton of a parent monomer. The resulting monomers, sharing the same C2 symmetry, were assembled with a D2h symmetric tetraamine to generate a dual-pore COF or single-pore COFs, depending on the sizes of the substituents, which were evidenced using PXRD studies and pore size distribution analyses...
May 1, 2017: Chemical Science
Yi Feng, Shoujun Zhu, Alexander L Antaris, Hao Chen, Yuling Xiao, Xiaowei Lu, Linlin Jiang, Shuo Diao, Kuai Yu, Yan Wang, Sonia Herraiz, Jingying Yue, Xuechuan Hong, Guosong Hong, Zhen Cheng, Hongjie Dai, Aaron J Hsueh
In vivo imaging of hormone receptors provides the opportunity to visualize target tissues under hormonal control in live animals. Detecting longer-wavelength photons in the second near-infrared window (NIR-II, 1000-1700 nm) region affords reduced photon scattering in tissues accompanied by lower autofluorescence, leading to higher spatial resolution at up to centimeter tissue penetration depths. Here, we report the conjugation of a small molecular NIR-II fluorophore CH1055 to a follicle stimulating hormone (FSH-CH) for imaging ovaries and testes in live mice...
May 1, 2017: Chemical Science
Kevin J Anderton, Brian J Knight, Arnold L Rheingold, Khalil A Abboud, Ricardo García-Serres, Leslie J Murray
The triiron trihydride complex Fe3H3L (1) [where L(3-) is a tris(β-diketiminate)cyclophanate] reacts with CO and with BF3·OEt2 to afford (Fe(I)CO)2Fe(II)(μ3-H)L (2) and Fe3F3L (3), respectively. Variable-temperature and applied-field Mössbauer spectroscopy support the assignment of two high-spin (HS) iron(i) centers and one HS iron(ii) ion in 2. Preliminary studies support a CO-induced reductive elimination of H2 from 1, rather than CO trapping a species from an equilibrium mixture. This complex reacts with H2 to regenerate 1 under a dihydrogen atmosphere, which represents a rare example of reversible CO/H2 exchange and the first to occur at high-spin metal centers, as well as the first example of a reversible multielectron redox reaction at a designed high-spin metal cluster...
May 1, 2017: Chemical Science
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