Search

Thiamphenicol (TM) is an antimicrobial drug and a methyl-sulfonyl analogue of chloramphenicol. New metal complexes of TM with Zn(II), Cu(II), Ni(II), Co(II) and Fe(II) were synthesized and characterized using elemental analyses, infrared (IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR), magnetic susceptibility, electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). The IR spectra revealed coordination of the deprotonated ligand to the metal through one oxygen and the nitrogen atom of the amide group. Moreover, EPR analysis of the Cu(II) solid sample indicated a distorted tetrahedral structure with a negligible exchange interaction between the Cu(II) ions. The UV-vis spectral results from the Co(II) and Fe(II) complexes showed a distorted tetrahedral geometric arrangement for both compounds. The DFT calculation approach was used to study the nature of the interaction between the metal ions and the ligand where the molecular stability and bond strengths were evaluated by Natural Bond Orbital (NBO) and quantum parameters. The biological activity of the metal complexes was investigated by several different bioassays. The DNA binding constant Kb showed an intercalation binding mode for both the free drug and the metal compounds. An in vitro protein (HSA) binding study showed binding with TM–Zn Kb = 9.87 × 105 M−1. The cytotoxic activity of each divalent complex was tested against two cell lines: (1) a human colon carcinoma (HCT-116) cell line and (2) a human breast carcinoma (MCF-7) tumor cell line and demonstrated anti-cancer cell activities. Molecular docking was utilized to explain the biological inhibition of the Cu(II) and Zn(II) complexes. [ABSTRACT FROM AUTHOR]

Molecular doping has been shown to improve the performance of various organic (opto)electronic devices. When compared to p-doped systems, research into n-doped organic small-molecules is relatively limited, primarily due to the lack of suitable dopants and the often encountered unfavourable microstructural effects. These factors have prevented the use of n-doping in a wider range of existing materials, such as non-fullerene acceptors (NFAs), that have already shown great promise for a range of (opto)electronic applications. Here, we show that several different molecular n-dopants, namely [1,2-b:2′,1′-d]benzo[i][2.5]benzodiazocine potassium triflate adduct (DMBI-BDZC), tetra-n-butylammonium fluoride (TBAF) and 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI), can be used to n-dope the molecular semiconductor O-IDTBR, a promising NFA, and increase the electron field-effect mobility to >1 cm2 V−1 s−1. By combining complementary experimental techniques with computer simulations of doping and charge carrier dynamics, we show that improved charge transport arises from synergistic effects of n-type doping and morphological changes. Specifically, a new, previously unreported dopant-induced packing orientation results in one of the highest electron mobility values reported to-date for an NFA molecule. Overall, this work highlights the importance of dopant–semiconductor interactions and their impact on morphology, showing that dopant-induced molecular packing motifs may be generic and a key element of the charge transport enhancement observed in doped organics. [ABSTRACT FROM AUTHOR]

Amadori products (deoxyfructosyllysine derivatives) that can selectively interact with phenylboronic acids and borate ions were synthesized. The intramolecular interactions between the fructosyl moiety and phenylboronic acid incorporated into various positions of the peptide chain were investigated using high-resolution mass spectrometry (HR–MS), circular dichroism (CD), and nuclear magnetic resonance (NMR). [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal carbides and/or nitrides (MXenes) have shown promise in developing electrochemical storage of metal ions within conductive galleries due to redox reactions with transition metal atoms. Here, effect of surface chemistry on electrochemical storage of sodium ions within MXene interlayers is investigated by etching Ti3AlC2 MAX using different etchants – HF, HF/HCl, and HF/H2SO4. [ABSTRACT FROM AUTHOR]

Three new quaternary compounds Na2BiSbQ4 (Q = S, Se, Te) have been synthesized by the direct combination reaction between Bi, Sb, Q and the corresponding Na2Q. All phases, sulfide, selenide and telluride, are isostructural and crystallize in the NaCl-type cubic space group Fm3̅m (no. 225) with lattice constants of a = 5.760(7), 5.964(9) and 6.331(5) Å, respectively. The unique feature of these structures is the existence of only one crystallographic metal site in the unit cell. These mixed position sites provide the desirable lattice complexity with a random distribution of the Na, Bi and Sb atoms. Consequently, extremely low thermal conductivities at room temperature have been observed for the studied phases. All three compounds are semiconductors and their Uv/Vis spectra exhibit redshifts toward narrower bandgap energies from sulfide to selenide to telluride. [ABSTRACT FROM AUTHOR]

A method for the synthesis of a homogeneous cationic tungsten(vi)pentamethyl complex [(WMe5)+(C6F5)3BMe−] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [(≡Si–O–)WMe4+ (C6F5)3BMe−] from a neutral silica supported tungstenpentamethyl complex [(≡Si–O–)WMe5] is described. In both cases a direct demethylation using the B(C6F5)3 reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)+(C6F5)3BMe−] shows moderate activity whereas the supported cationic complex [(≡Si–O–)WMe4+(C6F5)3BMe−] exhibits good activity in olefin metathesis reactions. [ABSTRACT FROM AUTHOR]

Herein, we report a facile approach towards the construction of poly-functional porous organic polymers (POPs). The functional groups employed were selected to span the range of Lewis-base to neutral to Lewis-acid character. Our results underline the effect of chemical functionality on the observed Qst for CO2 adsorption inside the material, being largest for functional groups with electron donating O- and N-centered Lewis base sites. Our systematic investigation within a family of POPs revealed a wide range for CO2 heat of adsorption (23.8–53.8 kJ mol−1) that is clearly associated with the chemical nature of the functional groups present. In addition, post-synthetic modification of POPs reported herein demonstrated a facile pathway to dramatically enhance carbon dioxide uptake energetics. [ABSTRACT FROM AUTHOR]

Cancer is a major cause of deaths across the globe due to chemoresistance and lack of selective chemotherapy. Pyrido[2,3- d ]pyrimidine is an emerging scaffold in medicinal chemistry having a broad spectrum of activities, including antitumor, antibacterial, CNS depressive, anticonvulsant, and antipyretic activities. In this study, we have covered different cancer targets, including tyrosine kinase, extracellular regulated protein kinases - ABL kinase, phosphatidylinositol-3 kinase, mammalian target of rapamycin, p38 mitogen-activated protein kinases, BCR-ABL, dihydrofolate reductase, cyclin-dependent kinase, phosphodiesterase, KRAS and fibroblast growth factor receptors, their signaling pathways, mechanism of action and structure-activity relationship of pyrido[2,3- d ]pyrimidine derivatives as inhibitors of the above-mentioned targets. This review will represent the complete medicinal and pharmacological profile of pyrido[2,3- d ]pyrimidines as anticancer agents, and will help scientists to design new selective, effective and safe anticancer agents., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)

The "RAS-RAF-MEK-ERK" pathway is an important signaling pathway in melanoma. BRAF V600E (70-90%) is the most common mutation in this pathway. BRAF inhibitors have four types of conformers: type I (αC-IN/DFG-IN), type II (αC-IN/DFG-OUT), type I 1/2 (αC-OUT/DFG-IN), and type I/II (αC-OUT/DFG-OUT). First- and second-generation BRAF inhibitors show resistance to BRAF V600E and are ineffective against malignancies induced by dimer BRAF mutants causing 'paradoxical' activation. In the present study, we performed molecular modeling of pyrimidine-sulfonamide hybrids inhibitors using 3D-QSAR, molecular docking, and molecular dynamics simulations. Previous reports reveal the importance of pyrimidine and sulfonamide moieties in the development of BRAF V600E inhibitors. Analysis of 3D-QSAR models provided novel pyrimidine sulfonamide hybrid BRAF V600E inhibitors. The designed compounds share similarities with several structural moieties present in first- and second-generation BRAF inhibitors. A total library of 88 designed compounds was generated and molecular docking studies were performed with them. Four molecules (T109, T183, T160, and T126) were identified as hits and selected for detailed studies. Molecular dynamics simulations were performed at 900 ns and binding was calculated. Based on molecular docking and simulation studies, it was found that the designed compounds have better interactions with the core active site [the nucleotide (ADP or ATP) binding site, DFG motif, and the phospho-acceptor site (activation segment) of BRAF V600E protein than previous inhibitors. Similar to the FDA-approved BRAF V600E inhibitors the developed compounds have [αC-OUT/DFG-IN] conformation. Compounds T126, T160 and T183 interacted with DIF (Leu505), making them potentially useful against BRAF V600E resistance and malignancies induced by dimer BRAF mutants. The synthesis and biological evaluation of the designed molecules is in progress, which may lead to some potent BRAF V600E selective inhibitors., Competing Interests: The authors declare no competing interest., (This journal is © The Royal Society of Chemistry.)

Here, we implemented and validated a suite of selective and non-selective CPMG-filtered 1D and 2D TOCSY/HSQC experiments for metabolomics research. They facilitated the unambiguous identification of metabolites embedded in broad lipid and protein signals. The 2D spectra improved non-targeted analysis by removing the background broad signals of macromolecules.

Two-dimensional transition metal carbides and/or nitrides (MXenes) have shown promise in developing electrochemical storage of metal ions within conductive galleries due to redox reactions with transition metal atoms. Here, effect of surface chemistry on electrochemical storage of sodium ions within MXene interlayers is investigated by etching Ti 3 AlC 2 MAX using different etchants - HF, HF/HCl, and HF/H 2 SO 4 .

The process of aggregation of proteins and peptides is dependent on the concentration of proteins, and the rate of aggregation can be altered by the presence of metal ions, but this dependence is not always a straightforward relationship. In general, aggregation does not occur under normal physiological conditions, yet it can be induced in the presence of certain metal ions. However, the extent of the influence of metal ion interactions on protein aggregation has not yet been fully comprehended. A consensus has thus been difficult to reach because the acceleration/inhibition of the aggregation of proteins in the presence of metal ions depends on several factors such as pH and the concentration of the aggregated proteins involved as well as metal concentration level of metal ions. Metal ions, like Cu 2+ , Zn 2+ , Pb 2+ etc. may either accelerate or inhibit aggregation simply because the experimental conditions affect the behavior of biomolecules. It is clear that understanding the relationship between metal ion concentration and protein aggregation will prove useful for future scientific applications. This review focuses on the dependence of the aggregation of selected important biomolecules (peptides and proteins) on metal ion concentrations. We review proteins that are prone to aggregation, the result of which can cause serious neurodegenerative disorders. Furthering our understanding of the relationship between metal ion concentration and protein aggregation will prove useful for future scientific applications, such as finding therapies for neurodegenerative diseases., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Dynamic nuclear polarization (DNP) has become an attractive technique to boost the sensitivity of NMR experiments. In the case of ex situ polarizations two-dimensional (2D) spectra are limited by the short lifetime of the polarization after dissolution and sample transfer to a high field NMR magnet. This limitation can be overcome by various approaches. Here we show how the use of (13)C-labelled acetyl tags can help to obtain 2D-HMQC spectra for many small molecules, owing to a nuclear Overhauser enhancement between (13)C spins originating from the long-lived carbonyl carbon, which extends the lifetimes of other (13)C spins with shorter longitudinal relaxation times. We also show an alternative approach of using an optimized polarization matrix.