Read by QxMD icon Read

Halogen Bonding

Panu Pimviriyakul, Panida Surawatanawong, Pimchai Chaiyen
Enzymes that are capable of detoxifying halogenated phenols (HPs) and nitrophenols (NPs) are valuable for bioremediation and waste biorefining. HadA monooxygenase was found to perform dual functions of oxidative dehalogenation (hydroxylation plus halide elimination) and denitration (hydroxylation plus nitro elimination). Rate constants associated with individual steps of HadA reactions with phenol, halogenated phenols and nitrophenols were measured using combined transient kinetic approaches of stopped-flow absorbance/fluorescence and rapid-quench flow techniques...
October 14, 2018: Chemical Science
Jérôme Graton, Seyfeddine Rahali, Jean-Yves Le Questel, Gilles Montavon, Julien Pilmé, Nicolas Galland
The nature of halogen-bond interactions is scrutinized from the perspective of astatine, the heaviest halogen element. Potentially the strongest halogen-bond donor, its ability is shown to be deeply affected by relativistic effects and especially by the spin-orbit coupling. Complexes between a series of XY dihalogens (X, Y = At, I, Br, Cl and F) and ammonia are studied with two-component relativistic quantum calculations, revealing that the spin-orbit interaction leads to a weaker halogen-bond donating ability of the diastatine species with respect to diiodine...
October 15, 2018: Physical Chemistry Chemical Physics: PCCP
Xicheng Yang, Jian Shen, Lulu Jiang, Wei Li, Mingcheng Yu, Guanxing Pan, Yurong Yan, Chenghan Zhang, Wanwan Jia, Li Xiao, Haihua Yu, Hao Chen, Yilin Zheng, Linqian Yu, Qiong Xie, Lu Zhou, Liming Shao
A series of novel pyridine-substituted piperidine derivatives were discovered as low nanomolar Ls-AChBP ligands with α7 nAChR partial agonism or antagonism activities. A high-resolution antagonist-bound Ls-AChBP complex was successfully resolved with a classic Loop C opening phenomenon and unique sulfur-π interactions which deviated from our previous docking mode to a large extent. With the knowledge of the co-complex, 27 novel piperidine derivatives were designed and synthesized. The structure-activity relationships (SARs) of the aromatic and pyridine regions were well established and binding modes were illustrated with the help of molecular docking which indicated that interactions with Trp 143 and the "water bridge" are essential for the high binding affinities...
October 3, 2018: European Journal of Medicinal Chemistry
Jama Ariai, Giacomo Saielli
We have investigated, using two-component relativistic density functional theory (DFT) at ZORA-SO-BP86 and ZORA-SO-PBE0 level, the occurrence of relativistic effects on the 1H, 13C, and 15N NMR chemical shifts of 1-methylpyridinium halides [MP][X] and 1-butyl-3-methylpyridinium trihalides [BMP][X3] ionic liquids (ILs) (X = Cl, Br, I) as a result of a non-covalent interaction with the heavy anions. Our results indicate a sizeable deshielding effect in ion pairs when the anion is I- and I3-. A smaller, though nonzero, effect is observed also with bromine while chlorine based anions do not produce an appreciable relativistic shift...
October 12, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Kiran Kumarvarma Chakrahari, Rhone P Brocha Silalahi, Jian-Hong Liao, Samia Kahlal, Yu-Chiao Liu, Jyh-Fu Lee, Ming-Hsi Chiang, Jean-Yves Saillard, C W Liu
We have synthesized and structurally characterized a series of centred cuboctahedral copper clusters, namely [Cu13 {S2 CNR2 }6 {C[triple bond, length as m-dash]CR'}4 ](PF6 ), 1a-d (where a : R = n Bu, R' = CO2 Me; b : R = n Bu, R' = CO2 Et; c : R = i Pr, R' = CO2 Et; d : R = n Pr, R' = 3,5-(CF3 )2 C6 H3 ); [Cu12 (μ12 -S){S2 CNR2 }6 {C[triple bond, length as m-dash]CR'}4 ], 2a-c ; [Cu12 (μ12 -Cl){S2 CNR2 }6 {C[triple bond, length as m-dash]CR'}4 ](PF6 ), 3a-e (where e : R = n Bu, R' = Ph); [Cu12 (μ12 -Br){S2 CN n Bu2 }6 {C[triple bond, length as m-dash]CPh}4 ](PF6 ), 4e ; and [Cu12 (μ12 -Cl)(μ3 -Cl){S2 CN n Bu2 }6 {C[triple bond, length as m-dash]CCO2 Me}3 ]+ 5a ...
September 7, 2018: Chemical Science
Christoph Kerzig, Oliver S Wenger
Sensitized triplet-triplet annihilation (TTA) is a promising mechanism for solar energy conversion, but so far its application has been practically completely limited to organic solvents and self-assembled or solid state systems. Combining water-soluble ruthenium complex-pyrene dyads with particularly long excited-state lifetimes as sensitizers and highly fluorescent commercial anthracenes as acceptors/annihilators, we were able to achieve green-to-violet upconversion with unprecedented quantum yields in pure water...
August 28, 2018: Chemical Science
Asia Marie S Riel, Daniel A Decato, Jiyu Sun, Casey J Massena, Morly J Jessop, Orion B Berryman
[This corrects the article DOI: 10.1039/C8SC01973H.].
August 14, 2018: Chemical Science
Zhaoxu Wang, Yi Liu, Baishu Zheng, Fengxiang Zhou, Yinchun Jiao, Yuan Liu, XunLei Ding, Tian Lu
Intermolecular interaction of XH2 P···MY (X = H, CH3 , F, CN, NO2 ; M = Cu, Ag, Au; Y = F, Cl, Br, I) complexes was investigated by means of an ab initio method. The molecular interaction energies are in the order Ag < Cu < Au and increased with the decrease of RP···M . Interaction energies are strengthened when electron-donating substituents X connected to XH2 P, while electron-withdrawing substituents produce the opposite effect. The strongest P···M bond was found in CH3 H2 P···AuF with -70...
May 21, 2018: Journal of Chemical Physics
Dan Shen, Peifeng Su, Wei Wu
The response of a series of neutral halogen bonds X'-XY (X'-X = BrF, ClF, I2, Br2 and Cl2; Y = pyridine, NH3, H2S, HCN, H2O and dimethyl ether) to solvent effects is investigated using quantum theory of atoms in molecules (AIM), molecular electrostatic potential (MESP) and generalized Kohn-Sham energy decomposition analysis (GKS-EDA). The physical origin of the halogen bonds in various environments is explored. It is shown that halogen bonds in the gas phase are indeed governed by electrostatic interactions...
October 11, 2018: Physical Chemistry Chemical Physics: PCCP
Shi Jun Ang, Adrian M Mak, Ming Wah Wong
The recently developed adiabatic absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) has proven to be useful in determining the effects of different energy components on the geometries of complexes bound by intermolecular interactions. The authors have applied it to systems such as the water dimer, water-ion complexes, metallocenes and lone-pair type halogen-bonded (XB) dimers. In this study, we have extended the second-generation ALMO-EDA method to 40 different XB complexes by benchmarking against its classical counterpart and symmetry-adapted perturbation theory (SAPT)...
October 11, 2018: Physical Chemistry Chemical Physics: PCCP
Ashok K Verma, P Modak
We propose a new metallic phase (R3[combining macron]m, Z = 24) for H3S in a large pressure interval (∼108-166 GPa) using an evolutionary crystal structure search algorithm combined with first-principles calculations. This structure consists of SH6, SH3 and S units which are connected through strong SH hydrogen-bonds. It supports four-types of SH hydrogen-bonds that symmetrize at ∼166 GPa. This is the only phase in the H-S family where sulfur exists in three different local environments. Sulfur in SH6 behaves as a cation, like in the SF6 molecule, whereas other sulfurs behave as anions...
October 10, 2018: Physical Chemistry Chemical Physics: PCCP
P Deepa, D Thirumeignanam, P Kolandaivel
Casein Kinase 2 (CK2) is extremely preserved and universally uttered serine/threonine kinase, vital for cellular feasibility. The present study was aimed to analyse the binding strength of CK2 ligands specifically in the hinge region, as it is aware that most of the existing drugs are targeted to bind the hinge of the corresponding protein. The analysis will give a clear picture about the role of hinge region with ligand, which will be useful for scientist community in drug designing. To predict the binding strength of CK2 ligands, the role of halogen bond, hydrogen bond interaction at the hinge region was depicted in detail through interaction energy calculations at M062Z/def2-QZVP level of theory...
October 9, 2018: Journal of Biomolecular Structure & Dynamics
Maciej Bujak
Tetrachlorobenzenes represent one of the best known, but not yet fully understood, group of isomers of the structure-melting point relationship. The differences in melting temperatures of these structurally related compounds were rationalized in terms of the hierarchy and nature of formed noncovalent interactions, and the molecular aggregation that is influenced by molecular symmetry. The highest melting point is associated with the highly symmetric 1,2,4,5-tetrachlorobenzene isomer. The structures of less symmetrical 1,2,3,4-tetrachlorobenzene and 1,2,3,5-tetrachlorobenzene, determined at 270 and 90 K, show a distinct pattern of halogen bonds, characterized by the different numbers and types of interactions...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
Robert G Surbella, Lucas C Ducati, Jochen Autschbach, Kristi L Pellegrini, Bruce K McNamara, Jon M Schwantes, Christopher L Cahill
Four new [Pu(iv)Cln(NO3)6-n]2- (n = 0, 2, 3) and [Pu(vi)O2Cl3(NO3)]2- containing materials were crystallized from acidic, aqueous media and structurally characterized. The anions are assembled via hydrogen and halogen bonding motifs, which are rationalized computationally. The Pu-NO3 and -Cl bonds were probed using QTAIM and NLMO analyses and found to be polar and largely ionic.
October 8, 2018: Chemical Communications: Chem Comm
Guo-Liang Qiu, Shao-Sheng He, Shi-Chao Chen, Bo Li, Hui-Hui Wu, Jing Zhang, Wen-Jian Tang
Based on the structural analysis of tricyclic scaffolds as butyrylcholinesterase (BuChE) inhibitors, a series of pyrazolo[1,5-c][1,3]benzoxazin-5(5H)-one derivatives were designed, synthesized and evaluated for their acetylcholinesterase (AChE) and BuChE inhibitory activity. Compounds with 5-carbonyl and 7- or/and 9-halogen substitutions showed potential BuChE inhibitory activity, among which compounds 6a, 6c and 6g showed the best BuChE inhibition (IC50  = 1.06, 1.63 and 1.63 µM, respectively). The structure-activity relationship showed that the 5-carbonyl and halogen substituents significantly influenced BuChE activity...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
Jyothish Joy, Edakkandy Akhil, Eluvathingal D Jemmis
Detailed electronic structural analysis of [1.1.1]propellane and the open form of [2.2.2]propellane, especially their highest occupied molecular orbital (HOMO), shows the existence of significant electronic congestion at their bridge bond. The HOMO of [1.1.1]propellane is a spread-out orbital of its inverted tetrahedral bridgehead atoms. The HOMO of the open form of [2.2.2]propellane is an anti-bonding combination of its bridgehead atoms due to the stabilizing through-bond interaction. This unique spatial disposition of the HOMO enables a high electron density at the bridgehead atoms...
October 4, 2018: Physical Chemistry Chemical Physics: PCCP
Juran Noh, Sungwoo Jung, Dong Geon Koo, Gyoungsik Kim, Kyoung Soon Choi, JaeHong Park, Tae Joo Shin, Changduk Yang, Juhyun Park
We fabricated nanowires of a conjugated oligomer and applied them to organic field-effect transistors (OFETs). The supramolecular assemblies of a thienoisoindigo-based small molecular organic semiconductor (TIIG-Bz) were prepared by co-precipitation with 2-bromobenzaldehyde (2-BBA) via a combination of halogen bonding (XB) between the bromide in 2-BBA and electron-donor groups in TIIG-Bz, and chalcogen bonding (CB) between the aldehyde in 2-BBA and sulfur in TIIG-Bz. It was found that 2-BBA could be incorporated into the conjugated planes of TIIG-Bz via XB and CB pairs, thereby increasing the π - π stacking area between the conjugated planes...
September 27, 2018: Scientific Reports
Jagadish K Salunke, Nikita A Durandin, Tero-Petri Ruoko, Nuno R Candeias, Paola Vivo, Elina Vuorimaa-Laukkanen, Timo Laaksonen, Arri Priimagi
Halogen bonding between a carbazole-based, pyridine-substituted organic semiconductor and a common halogen-bond donor (pentafluoroiodobenzene) yields efficient halogen-bond-driven fluorescence modulation in solution. Steady-state, time-resolved emission and absorption spectroscopy as well as density functional theory studies demonstrate that the fluorescence modulation arises from halogen-bond-induced intramolecular charge transfer. Fluorescence modulation offers a range of possibilities both in solution and in the solid state, for instance providing a potential pathway for the design of tunable luminescent materials for light-emitting devices...
September 26, 2018: Scientific Reports
Zdeněk Pilát, Martin Kizovský, Jan Ježek, Stanislav Krátký, Jaroslav Sobota, Martin Šiler, Ota Samek, Tomáš Buryška, Pavel Vaňáček, Jiří Damborský, Zbyněk Prokop, Pavel Zemánek
Optofluidics, a research discipline combining optics with microfluidics, currently aspires to revolutionize the analysis of biological and chemical samples, e.g., for medicine, pharmacology, or molecular biology. In order to detect low concentrations of analytes in water, we have developed an optofluidic device containing a nanostructured substrate for surface enhanced Raman spectroscopy (SERS). The geometry of the gold surface allows localized plasmon oscillations to give rise to the SERS effect, in which the Raman spectral lines are intensified by the interaction of the plasmonic field with the electrons in the molecular bonds...
September 23, 2018: Sensors
Wei Zhang, Jia Chen, Jin-Hong Lin, Ji-Chang Xiao, Yu-Cheng Gu
The CF3 O functional group is a unique fluorinated group that has received a great deal of attention in medicinal chemistry and agrochemistry. However, trifluoromethoxylation of substrates remains a challenging task. Herein we describe the dehydroxytrifluoromethoxylation of alcohols promoted by a R3 P/ICH2 CH2 I (R3 P = Ph3 P or Ph2 PCH=CH2 ) system in DMF. P-I halogen bonding drives the reaction of R3 P with ICH2 CH2 I in DMF to generate iodophosphonium salt (R3 P+ I I- ) and a Vilsmeier-Haack-type intermediate, both of which could effectively activate alcohols, thus enabling a fast (15 min) trifluoromethoxylation reaction...
July 27, 2018: iScience
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"