scholarly journals Deciphering the H-Bonding Preference on Nucleoside Molecular Recognition through Model Copper(II) Compounds

2021 ◽  
Vol 14 (3) ◽  
pp. 244
Author(s):  
Inmaculada Velo-Gala ◽  
Miquel Barceló-Oliver ◽  
Diego M. Gil ◽  
Josefa M. González-Pérez ◽  
Alfonso Castiñeiras ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Magnetic Measurements ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Vis Spectroscopy ◽  
Non Covalent Interactions ◽  
Electron Paramagnetic ◽  
Covalent Interactions ◽  
Coordination Plane

The synthetic nucleoside acyclovir is considered an outstanding model of the natural nucleoside guanosine. With the purpose of deepening on the influence and nature of non-covalent interactions regarding molecular recognition patterns, three novel Cu(II) complexes, involving acyclovir (acv) and the ligand receptor N-(2-hydroxyethyl)ethylenediamine (hen), have been synthesized and thoroughly characterized. The three novel compounds introduce none, one or two acyclovir molecules, respectively. Molecular recognition has been evaluated using single crystal X-ray diffraction. Furthermore, theoretical calculations and other physical methods such as thermogravimetric analysis, infrared and UV-Vis spectroscopy, electron paramagnetic resonance and magnetic measurements have been used. Theoretical calculations are in line with experimental results, supporting the relevance of the [metal-N7(acv) + H-bond] molecular recognition pattern. It was also shown that (hen)O-H group is used as preferred H-donor when it is found within the basal coordination plane, since the higher polarity of the terminal (hen)O-H versus the N-H group favours its implication. Otherwise, when (hen)O-H occupies the distal coordination site, (hen)N-H groups can take over.

Fabrication, characterization and magnetic properties of Na-doped ZnO nanorods

2016 ◽  
Vol 09 (03) ◽  
pp. 1650039 ◽  
Author(s):  
Jingyuan Piao ◽  
Li-Ting Tseng ◽  
Kiyonori Suzuki ◽  
Jiabao Yi
Keyword(s):  
Magnetic Measurements ◽  
Zno Nanorods ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Shallow Donors ◽  
Na Doping ◽  
Transmission Electron ◽  
Doped Zno ◽  
Electron Paramagnetic

Na-doped ZnO nanorods have been fabricated through a hydrothermal method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses indicate that the d spacing of ZnO increases with increasing doping concentration, suggesting the effective incorporation of dopant Na in the samples. Electron paramagnetic resonance (EPR) measurements indicate that there are shallow donors in pure ZnO samples and the shallow donors are strongly prohibited by Na doping. In addition, the resonance at g = 2.005 suggests the formation of Zn vacancies. Magnetic measurements indicate that pure ZnO is paramagnetic and Na doping leads to ferromagnetism at room temperature. Moreover, 0.5% Na-doped ZnO nanorods exhibits the largest saturation magnetization.

Dinuclear Cu(II) 1,2,3-Triazole-Bridged Complex with Ferromagnetic Coupling

2013 ◽  
Vol 66 (9) ◽  
pp. 1029 ◽  
Author(s):  
Shi-Qiang Bai ◽  
Lu Jiang ◽  
Jing-Lin Zuo ◽  
Chun-Hua Yan ◽  
T. S. Andy Hor
Keyword(s):  
Resonance Spectrum ◽  
Magnetic Measurements ◽  
Ferromagnetic Coupling ◽  
X Ray Diffraction ◽  
Asymmetric Mode ◽  
Paramagnetic Resonance ◽  
Ferromagnetic Interaction ◽  
X Ray ◽  
Electron Paramagnetic ◽  
Weak Ferromagnetic

A new dinuclear Cu(ii) complex [Cu2Cl4(L1)2] (1) (L1 = 1-(2-picolyl)-4-hexyl-1H-1,2,3-triazole) has been synthesised and characterised by single-crystal X-ray diffraction (XRD) and powder XRD, thermogravimetric analysis, electron paramagnetic resonance spectrum, photoluminescence, and magnetic measurements. Complex 1 shows double 1,2,3-triazoles bridging the dinuclear Cu2N4 moiety, in which the bridging N=N bond indicates basal-apical asymmetric mode with 112.6° torsion angle of Cu–N=N–Cu. Different from most azole-bridged dinuclear Cu(ii) with antiferromagnetic couplings, complex 1 shows an intramolecular weak ferromagnetic interaction (J = 0.91 cm–1).

scholarly journals Stable Helicene Radicals: Synthesis, Structure, Physical Properties, and Photocatalysis

2020 ◽  
Author(s):  
Aslam Shaikh ◽  
Md Mubarak Hossain ◽  
Jules Moutet ◽  
Jose Veleta ◽  
Jan Bloch ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reduction ◽  
Organic Radicals ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Neutral Radical ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic ◽  
Helical Molecules

Abstract Stable organic radicals have gained considerable attention in the fields of catalysis and material sciences. In particular, helical molecules are of great interest in the development and application of novel organic radicals in optoelectronic and spintronic materials. Here we report the syntheses of highly stable neutral quinolinoacridine radicals by chemical reduction of their quinolinoacridinium cation analogs. The crystal structures of these [4]helicene radicals were determined by X-ray diffraction. Electron paramagnetic resonance (EPR) measurements, supported by density functional theory (DFT) calculations, indicate that the unpaired electron is mostly localized, showing more than 40% of spin density located at the central carbon of the [4]helicene radicals. Quantitative conversion from neutral radical to cation is observed upon exposure to air, monitored via UV-vis spectroscopy. The successful photoreductive dehalogenation of aryl halides occurs in the presence of 10 mol% of [4]helicene radical under blue light.

scholarly journals Stable Helicene Radicals: Synthesis, Structure, Physical Properties, and Photocatalysis

2020 ◽  
Author(s):  
Aslam Shaikh ◽  
Md Mubarak Hossain ◽  
Jules Moutet ◽  
Jose M Veleta ◽  
jan bloch ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Reduction ◽  
Organic Radicals ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Neutral Radical ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic ◽  
Helical Molecules

<p>Stable organic radicals have gained considerable attention in the fields of catalysis and material sciences. In particular, helical molecules are of great interest in the development and application of novel organic radicals in optoelectronic and spintronic materials. Here we report the syntheses of highly stable neutral quinolinoacridine radicals by chemical reduction of their quinolinoacridinium cation analogs. The crystal structures of these [4]helicene radicals were determined by X-ray diffraction. Electron paramagnetic resonance (EPR) measurements, supported by density functional theory (DFT) calculations, indicate that the unpaired electron is mostly localized, showing more than 40% of spin density located at the central carbon of the [4]helicene radicals. Quantitative conversion from neutral radical to cation is observed upon exposure to air, monitored via UV-vis spectroscopy. The successful photoreductive dehalogenation of aryl halides occurs in the presence of 10 mol% of [4]helicene radical under blue light.<b></b></p>

scholarly journals Evaluation of the stability of cucurbit[8]uril-based ternary host−guest complexation in physiological environment and the fabrication of a supramolecular theranostic nanomedicine

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Han Wu ◽  
Zuobing Chen ◽  
Shaolong Qi ◽  
Bing Bai ◽  
Jiajun Ye ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Isothermal Titration Calorimetry ◽  
Disease Diagnosis ◽  
Titration Calorimetry ◽  
Resonance Spectroscopy ◽  
Diagnosis And Therapy ◽  
Vis Spectroscopy ◽  
Non Covalent Interactions ◽  
The Stability ◽  
Covalent Interactions

Abstract Background Supramolecular theranostics have exhibited promising potentials in disease diagnosis and therapy by taking advantages of the dynamic and reversible nature of non-covalent interactions. It is extremely important to figure out the stability of the driving forces in physiological environment for the preparation of theranostic systems. Methods The host−guest complexation between cucurbit[8]uril (CB[8]), 4,4′-bipyridinium, and napththyl guest was fully studied using various characterizations, including nuclear magnetic resonance spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, isothermal titration calorimetry (ITC). The association constants of this ternary complex were determined using isothermal titration calorimetry. The stability of the non-covalent interactions and self-assemblies form from this molecular recognition was confirmed by UV–vis spectroscopy and dynamic light scattering (DLS). A supramolecular nanomedicine was constructed on the basis of this 1:1:1 ternary recognition, and its in vitro and in vivo anticancer efficacy were thoroughly evaluated. Positron emission tomography (PET) imaging was used to monitor the delivery and biodistribution of the supramolecular nanomedicine. Results Various experiments confirmed that the ternary complexation between 4,4′-bipyridinium, and napththyl derivative and CB[8] was stable in physiological environment, including phosphate buffered solution and cell culture medium. Supramolecular nanomedicine (SNM@DOX) encapsulating a neutral anticancer drug (doxrubincin, DOX) was prepared based on this molecular recognition that linked the hydrophobic poly(ε-caprolactone) chain and hydrophilic polyethylene glycol segment. The non-covalent interactions guaranteed the stability of SNM@DOX during blood circulation and promoted its tumor accumulation by taking advantage of the enhanced permeability and retention effect, thus greatly improving the anti-tumor efficacy as compared with the free drug. Conclusion Arising from the host-enhanced charge-transfer interactions, the CB[8]-based ternary recognition was stable enough in physiological environment, which was suitable for the fabrication of supramolecular nanotheranostics showing promising potentials in precise cancer diagnosis and therapy. Graphic Abstract

scholarly journals Evaluation of the stability of cucurbit[8]uril-based ternary host−guest complexation in physiological environment and the fabrication of a supramolecular theranostic nanomedicine

2021 ◽  
Author(s):  
Han Wu ◽  
Zuobing Chen ◽  
Shaolong Qi ◽  
Bing Bai ◽  
Jiajun Ye ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Isothermal Titration Calorimetry ◽  
Titration Calorimetry ◽  
Resonance Spectroscopy ◽  
Vis Spectroscopy ◽  
Non Covalent Interactions ◽  
The Stability ◽  
Covalent Interactions

Abstract PurposeTo evaluate the stability of cucurbit[8]uril-based 1:1:1 ternary host−guest complexation in physiological environment for the fabrication of supramolecular theranostics with promising potentials in precise cancer imaging and therapy. MethodsThe host−guest complexation between cucurbit[8]uril (CB[8]), 4,4′-bipyridinium, and napththyl guest was fully studied using various characterizations, including nuclear magnetic resonance spectroscopy ( 1 H NMR), ultraviolet-visible (UV-vis) spectroscopy, isothermal titration calorimetry (ITC). The association constants of this ternary complex were determined using isothermal titration calorimetry. The stability of the non-covalent interactions and self-assemblies form from this molecular recognition was confirmed by UV-vis spectroscopy and dynamic light scattering (DLS). A supramolecular nanomedicine was constructed on the basis of this 1:1:1 ternary recognition, and its in vitro and in vivo anticancer efficacy were thoroughly evaluated. Positron emission tomography (PET) imaging was used to monitor the delivery and biodistribution of the supramolecular nanomedicine. ResultsVarious experiments confirmed that the ternary complexation between 4,4′-bipyridinium, and napththyl derivative and CB[8] was stable in physiological environment, including phosphate buffered solution and cell culture medium. Supramolecular nanomedicine (SNM@DOX) encapsulating a neutral anticancer drug (doxrubincin, DOX) was prepared based on this molecular recognition that linked the hydrophobic poly(ε-caprolactone) chain and hydrophilic polyethylene glycol segment. The non-covalent interactions guaranteed the stability of SNM@DOX during blood circulation and promoted its tumor accumulation by taking advantage of the enhanced permeability and retention effect, thus greatly improving the anti-tumor efficacy as compared with the free drug. ConclusionArising from the host-enhanced charge-transfer interactions, the CB[8]-based ternary recognition was stable enough in physiological environment, which was suitable for the fabrication of supramolecular nanotheranostics showing promising potentials in precise cancer diagnosis and therapy.

scholarly journals Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2123
Author(s):  
Maria Râpă ◽  
Maria Stefan ◽  
Paula Popa ◽  
Dana Toloman ◽  
Cristian Leostean ◽  
...  
Keyword(s):  
Food Packaging ◽  
Spin Trapping ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Hno3 Solution ◽  
X Ray ◽  
Trapping Method ◽  
Ft Ir ◽  
Doped Zno ◽  
Electron Paramagnetic

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

scholarly journals On the Proton-Bound Noble Gas Dimers (Ng-H-Ng)+ and (Ng-H-Ng')+ (Ng, Ng'= He-Xe): Relationships betweenStructure, Stability, and Bonding Character

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1305
Author(s):  
Stefano Borocci ◽  
Felice Grandinetti ◽  
Nico Sanna
Keyword(s):  
Theoretical Calculations ◽  
Noble Gas ◽  
Structure Stability ◽  
Covalent Bonds ◽  
Dissociation Energies ◽  
Non Covalent Interactions ◽  
The Difference ◽  
Noble Gas Dimers ◽  
Covalent Interactions ◽  
Cluster Level

The structure, stability, and bonding character of fifteen (Ng-H-Ng)+ and (Ng-H-Ng')+ (Ng, Ng' = He-Xe) compounds were explored by theoretical calculations performed at the coupled cluster level of theory. The nature of the stabilizing interactions was, in particular, assayed using a method recently proposed by the authors to classify the chemical bonds involving the noble-gas atoms. The bond distances and dissociation energies of the investigated ions fall in rather large intervals, and follow regular periodic trends, clearly referable to the difference between the proton affinity (PA) of the various Ng and Ng'. These variations are nicely correlated with the bonding situation of the (Ng-H-Ng)+ and (Ng-H-Ng')+. The Ng-H and Ng'-H contacts range, in fact, between strong covalent bonds to weak, non-covalent interactions, and their regular variability clearly illustrates the peculiar capability of the noble gases to undergo interactions covering the entire spectrum of the chemical bond.

scholarly journals Synthesis, Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4331
Author(s):  
David B. Hobart ◽  
Michael A. G. Berg ◽  
Hannah M. Rogers ◽  
Joseph S. Merola
Keyword(s):  
Amino Acid ◽  
High Resolution Mass Spectrometry ◽  
Resonance Spectroscopy ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
Amino Acid Complexes ◽  
Acetone Water ◽  
Square Planar ◽  
Non Covalent Interactions ◽  
Covalent Interactions

The reaction of palladium(II) acetate with acyclic amino acids in acetone/water yields square planar bis-chelated palladium amino acid complexes that exhibit interesting non-covalent interactions. In all cases, complexes were examined by multiple spectroscopic techniques, especially HRMS (high resolution mass spectrometry), IR (infrared spectroscopy), and 1H NMR (nuclear magnetic resonance) spectroscopy. In some cases, suitable crystals for single crystal X-ray diffraction were able to be grown and the molecular structure was obtained. The molecular geometries of the products are discussed. Except for the alanine complex, all complexes incorporate water molecules into the extended lattice and exhibit N-H···O and/or O···(HOH)···O hydrogen bonding interactions. The non-covalent interactions are discussed in terms of the extended lattice structures exhibited by the structures.

Sign in / Sign up

Export Citation Format

Share Document