Search results for "Azide"
showing 10 items of 334 documents
Azide and chloride binding to carboxypeptidase A in the presence of L-phenylalanine
1990
The interaction of chloride with native and cobalt (Co)-substituted carboxypeptidase-A (CPD) has been investigated by 35Cl nuclear magnetic resonance (NMR) spectroscopy in the presence and absence of L-Phe. The affinity constants of azide and chloride toward the Co(II)CPD·L-Phe complex have been measured by electronic spectroscopy. The correlation times determining T1 and T2 for the 35Cl nuclei are related to movements inside the cavity. In the presence of L-Phe, the anions bind to the metal with a relatively high affinity at pH values below 6. Anion binding to the Co enzyme can be analyzed in terms of the three protonation state model for the enzyme (EH2 α EH α E). In the presence of L-Phe…
CCDC 816864: Experimental Crystal Structure Determination
2014
Related Article: Manas Sutradhar, Tannistha Roy Barman, Eva Rentschler|2014|Inorg.Chem.Commun.|39|140|doi:10.1016/j.inoche.2013.11.018
CCDC 1422395: Experimental Crystal Structure Determination
2016
Related Article: I. Sarceviča, A. Kons, L. Orola|2016|CrystEngComm|18|1625|doi:10.1039/C5CE01774B
Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges
2019
Two mixtures of polyaminoazides were synthesized by a nucleophilic displacement strategy providing no separation of the components. The mixtures were adequately characterized by means of combined HR-ESIMS, FTIR and NMR techniques and, despite their complexity, they were successfully used to accomplish the subsequent preparation of pH-sensitive calixarene hyper-reticulated nanosponge materials. The desired responsivity to pH variations of the nanosponges obtained was verified by means of absorption tests on a set of organic pollutant model molecules.
Synthesis of Globular Precursors
2015
o-Carborane (C2 B10 H12 ) was adapted to perform as the core of globular macromolecules, dendrons or dendrimers. To meet this objective, precisely defined substitution patterns of terminal olefin groups on the carborane framework were subjected to Heck cross-coupling reactions or hydroboration leading to hydroxyl terminated arms. These led to new terminal groups (chloro, bromo, and tosyl leaving groups, organic acid, and azide) that permitted ester production, click chemistry, and oxonium ring opening to be performed as examples of reactions that demonstrate the wide possibilities of the globular icosahedral carboranes to produce new dendritic or dendrimer-like structures. Polyanionic speci…
Understanding the mechanism and regioselectivity of the copper(i) catalyzed [3 + 2] cycloaddition reaction between azide and alkyne: a systematic DFT…
2017
The copper(I) catalyzed azide–alkyne [3 + 2] cycloaddition (32CA) reaction and its uncatalyzed version have been studied for systematic understanding of this relevant organic transformation, using DFT calculations at the B3LYP/6-31G(d) (LANL2DZ for Cu) computational levels. In the absence of a copper(I) catalyst, two regioisomeric reaction paths were studied, indicating that the 32CA reaction takes place through an asynchronous one-step mechanism with a very low polar character. The two reactive channels leading to 1,4- and 1,5-regisomer present similar high activation energies of 18.84 and 18.51 kcal mol−1, respectively. The coordination of copper(I) to alkyne produces relevant changes in …
Organic chelate-free and azido-rich metal clusters and coordination polymers from the use of Me3SiN3: a new synthetic route to complexes with beautif…
2019
In this Feature Article, we highlight the feasibility of a new, recently developed approach towards the synthesis of high-spin molecules and single-molecule magnets (SMMs). The key to the preparation of such molecular compounds is the organic azide precursor Me3SiN3, which fosters the formation of 3d-metal azido clusters and coordination polymers without requiring the assistance of any organic chelating/bridging group. All the isolated compounds contain metallic cores which are surrounded by end-on bridging N3− groups. Consequently, the reported molecular materials exhibit ferromagnetic exchange interactions between the spin carriers, resulting in the stabilization of the maximum possible s…
Facile immobilization of copper(I) acetate on silica: A recyclable and reusable heterogeneous catalyst for azide–alkyne clickable cycloaddition react…
2019
Abstract The structurally well-defined copper(I) acetate was immobilized on silica gel via electrostatic interactions. The catalytic activity of the immobilized catalyst Cu(I)–SiO2 was examined in the click synthesis of 1,2,3-triazoles in water/ethanol at room temperature. The catalyst showed high catalytic activity and regioselectivity for the Huisgen [3+2] cycloaddition reaction between terminal alkynes and azides. The catalyst was recovered by simple filtration and reused for up to five times. The analysis of the local electrophilicity/nucleophilicity has been performed on the dinuclear copper–acetylide complex intermediate. Conceptual DFT (CDFT) analysis enabled the explanation of the f…
The ultrasounds-ionic liquids synergy on the copper catalyzed azide-alkyne cycloaddition between phenyl acetylene and 4-azidoquinoline
2015
Abstract The effect of ultrasound irradiation on the copper catalyzed azide–alkyne cycloaddition between phenylacetylene and 4-azidoquinoline has been studied in solution of different ionic liquids. In particular, we used ionic liquids featuring both aliphatic and aromatic mono- and dications, as well as anions differing in size, symmetry and coordination ability. We also examined the influence of the ionic liquids structural features on the reaction outcomes, finding that under magnetic stirring reactivity is favorably affected by the solvent structural organization, while under sonochemical conditions an opposite trend was observed. In all cases examined, sonochemical activation leads to …
Low-Temperature Optical Spectroscopy of Native and Azide-Reacted Bovine Cu,Zn Superoxide Dismutase. A Structural Dynamics Study
1994
The optical absorption spectra of native and N(3-)-reacted Cu,Zn superoxide dismutase (SOD) has been studied in the temperature range 300-10 K. The broad d-d bands observed in the room temperature spectrum, centered at 14,700 cm-1 (native enzyme) and at 15,550 cm-1 (N(3-)-reacted enzyme), are clearly split at low temperature into two bands each, centered at 12,835 and 14,844 cm-1 and at 14,418 and 16,300 cm-1, respectively. The thermal behavior of the 23,720 cm-1 band present in the spectrum of the native enzyme indicates that this band belongs to the His61-->Cu(II) ligand to metal charge transfer transition. Analysis of the zeroth, first, and second moments of the various bands as a functi…