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Fundamental Aspects of Chemical Bonding

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Computational and Theoretical Chemistry".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 24558

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Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, 157 84 Zografou, Greece
Interests: computational and theoretical chemistry; ab initio calculations; DFT calculations; encapsulation; molecular logic gates; molecular sensors; photoinduced charge transfer processes; supramolecular systems; bonding analysis
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Dear Colleagues,

The chemical bond is one of the most fundamental concepts in chemistry. It explains why atoms are attracted to each other or why chemical reactions occur. There are two main categories of chemical bond based on their strength, namely, primary or strong bonds, i.e., covalent, metallic and ionic bonds, and secondary or weak bonds, i.e., dipole–dipole interactions, hydrogen bonds, etc. Different approaches are used for describing chemical bonding, i.e., molecular–orbital (MO), valence–bond (VB), electron localization function (ELF), quantum theory of atoms in molecules (QTAIM), etc.

Given that the making and breaking of bonds is the heart of chemistry, a lot of research is being conducted in order to clarify and understand bonding. This Special Issue aims to gather new ideas and methodologies on all aspects of chemical bonding as well as research studies on complex systems. Contributions in the form of original research or review articles are particularly welcome.

Dr. Demeter Tzeli
Guest Editor

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Keywords

  • chemical bonding
  • bonding analysis
  • calculations
  • interactions
  • MO analysis
  • VB analysis
  • electron localization function (ELF)
  • quantum theory of atoms in molecules (QTAIM)

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Published Papers (14 papers)

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Research

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14 pages, 12701 KiB  
Article
Experimental and Theoretical Screening of Core Gold Nanoparticles and Their Binding Mechanism to an Anticancer Drug, 2-Thiouracil
by Génesis Lorenzana-Vázquez, Daniel G. Adams, Lauren G. Reyna, Enrique Meléndez and Ioana E. Pavel
Molecules 2024, 29(1), 121; https://doi.org/10.3390/molecules29010121 - 24 Dec 2023
Viewed by 1350
Abstract
This study demonstrated the capability of two readily available optical spectroscopy tools, namely UV-Vis absorption spectrophotometry and Raman/surface-enhanced Raman spectroscopy, to select in a rapid and noninvasive manner the most homogenous gold nanoparticle (AuNP) models and to identify their chemical binding mechanism to [...] Read more.
This study demonstrated the capability of two readily available optical spectroscopy tools, namely UV-Vis absorption spectrophotometry and Raman/surface-enhanced Raman spectroscopy, to select in a rapid and noninvasive manner the most homogenous gold nanoparticle (AuNP) models and to identify their chemical binding mechanism to 2-thiouracil (2-TU). 2-TU is an anticancer drug of great promise in the antiproliferative and photothermal therapies of cancer. The citrate-capped AuNPs emerged as the most stable as well as time- and cost-effective AuNP model out of the three widely used colloidal nanocores (citrate-, borohydride-citrate-, and sodium dodecyl sulfate (SDS)-capped AuNPs) that were examined. 2-TU chemically attached to the relatively monodispersed AuNPs via a chemisorption mechanism. The 2-TU-AuNPs complex formed through the covalent bonding of the S atom of 2-TU to the nanosurface in a vertical orientation. The spectroscopic results were then confirmed with the help of density functional theory (DFT) calculations and other physicochemical characterization tools for nanomaterials such as transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential. Overall, the purified 2-TU-AuNPs were found to be spherical, had an average diameter of 25 ± 2 nm, a narrow size distribution (1–30 nm), a sharp localized surface plasmon resonance (LSPR) peak at 525 nm, and a negative surface charge (−14 mV). Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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29 pages, 3266 KiB  
Article
Electronic Structure and Chemical Bonding of the First-, Second-, and Third-Row-Transition-Metal Monoborides: The Formation of Quadruple Bonds in RhB, RuB, and TcB
by Constantinos Demetriou, Christina Eleftheria Tzeliou, Alexandros Androutsopoulos and Demeter Tzeli
Molecules 2023, 28(24), 8016; https://doi.org/10.3390/molecules28248016 - 8 Dec 2023
Viewed by 995
Abstract
Boron presents an important role in chemistry, biology, and materials science. Diatomic transition-metal borides (MBs) are the building blocks of many complexes and materials, and they present unique electronic structures with interesting and peculiar properties and a variety of bonding schemes which are [...] Read more.
Boron presents an important role in chemistry, biology, and materials science. Diatomic transition-metal borides (MBs) are the building blocks of many complexes and materials, and they present unique electronic structures with interesting and peculiar properties and a variety of bonding schemes which are analyzed here. In the first part of this paper, we present a review on the available experimental and theoretical studies on the first-row-transition-metal borides, i.e., ScB, TiB, VB, CrB, MnB, FeB, CoB, NiB, CuB, and ZnB; the second-row-transition-metal borides, i.e., YB, ZrB, NbB, MoB, TcB, RuB, RhB, PdB, AgB, and CdB; and the third-row-transition-metal borides, i.e., LaB, HfB, TaB, WB, ReB, OsB, IrB, PtB, AuB, and HgB. Consequently, in the second part, the second- and third-row MBs are studied via DFT calculations using the B3LYP, TPSSh, and MN15 functionals and, in some cases, via multi-reference methods, MRCISD+Q, in conjunction with the aug-cc-pVQZ-PPM/aug-cc-pVQZB basis sets. Specifically, bond distances, dissociation energies, frequencies, dipole moments, and natural NPA charges are reported. Comparisons between MB molecules along the three rows are presented, and their differences and similarities are analyzed. The bonding of the diatomic borides is also described; it is found that, apart from RhB(X1Σ+), which was just recently found to form quadruple bonds, RuB(X2Δ) and TcB(X3Σ) also form quadruple σ2σ2π2π2 bonds in their X states. Moreover, to fill the gap existing in the current literature, here, we calculate the TcB molecule. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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26 pages, 6925 KiB  
Article
A Series of Novel 3D Coordination Polymers Based on the Quinoline-2,4-dicarboxylate Building Block and Lanthanide(III) Ions—Temperature Dependence Investigations
by Dmytro Vlasyuk, Renata Łyszczek, Liliana Mazur, Agnieszka Pladzyk, Zbigniew Hnatejko and Przemysław Woźny
Molecules 2023, 28(17), 6360; https://doi.org/10.3390/molecules28176360 - 30 Aug 2023
Cited by 3 | Viewed by 1069
Abstract
A series of novel 3D coordination polymers [Ln2(Qdca)3(H2O)x]·yH2O (x = 3 or 4, y = 0–4) assembled from selected lanthanide ions (Ln(III) = Nd, Eu, Tb, and Er) and a non-explored quinoline-2,4-dicarboxylate building [...] Read more.
A series of novel 3D coordination polymers [Ln2(Qdca)3(H2O)x]·yH2O (x = 3 or 4, y = 0–4) assembled from selected lanthanide ions (Ln(III) = Nd, Eu, Tb, and Er) and a non-explored quinoline-2,4-dicarboxylate building block (Qdca2− = C11H5NO42−) were prepared under hydrothermal conditions at temperatures of 100, 120, and 150 °C. Generally, an increase in synthesis temperature resulted in structural transformations and the formation of more hydrated compounds. The metal complexes were characterized by elemental analysis, single-crystal and powder X-ray diffraction methods, thermal analysis (TG-DSC), ATR/FTIR, UV/Vis, and luminescence spectroscopy. The structural variety of three-dimensional coordination polymers can be ascribed to the temperature effect, which enforces the diversity of quinoline-2,4-dicarboxylate ligand denticity and conformation. The Qdca2− ligand only behaves as a bridging or bridging–chelating building block binding two to five metal centers with seven different coordination modes arising mainly from different carboxylate group coordination types. The presence of water molecules in the structures of complexes is crucial for their stability. The removal of both coordinated and non-coordinated water molecules leads to the disintegration and combustion of metal–organic frameworks to the appropriate lanthanide oxides. The luminescence features of complexes, quantum yield, and luminescent lifetimes were measured and analyzed. Only the Eu complexes show emission in the VIS region, whereas Nd and Er complexes emit in the NIR range. The luminescence properties of complexes were correlated with the crystal structures of the investigated complexes. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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22 pages, 9468 KiB  
Article
Bader’s Topological Bond Path Does Not Necessarily Indicate Stabilizing Interaction—Proof Studies Based on the Ng@[3n]cyclophane Endohedral Complexes
by Mirosław Jabłoński
Molecules 2023, 28(17), 6353; https://doi.org/10.3390/molecules28176353 - 30 Aug 2023
Cited by 3 | Viewed by 930
Abstract
According to Bader’s quantum theory of atoms in molecules (QTAIM), the simultaneous presence of a bond path and the corresponding bond critical point between any two atoms is both a necessary and sufficient condition for the atoms to be bonded to one another. [...] Read more.
According to Bader’s quantum theory of atoms in molecules (QTAIM), the simultaneous presence of a bond path and the corresponding bond critical point between any two atoms is both a necessary and sufficient condition for the atoms to be bonded to one another. In principle, this means that this pair of atoms should make a stabilizing contribution to the molecular system. However, the multitude of so-called counterintuitive bond paths strongly suggests that this statement is not necessarily true. Particularly ‘troublesome’ are endohedral complexes, in which encapsulation-enforced proximity between the trapped guest (e.g., an atom) and the host’s cage system usually ‘produces’ many counterintuitive bond paths. In the author’s opinion, the best evidence to demonstrate the repulsive nature of the intra-cage guest⋯host interaction is the use of some trapping systems containing small escape channels and then showing that the initially trapped entity spontaneously escapes outside the host’s cage during geometry optimization of the initially built guest@host endohedral complex. For this purpose, a group of 24 Ng@[3n]cyclophane (3n6) endohedral complexes is used. As a result, arguments are presented showing that Bader’s topological bond path does not necessarily indicate a stabilizing interaction. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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24 pages, 698 KiB  
Article
Complexes of HXeY with HX (Y, X = F, Cl, Br, I): Symmetry-Adapted Perturbation Theory Study and Anharmonic Vibrational Analysis
by Bartosz Dzięcioł, Irina Osadchuk, Janusz Cukras and Jan Lundell
Molecules 2023, 28(13), 5148; https://doi.org/10.3390/molecules28135148 - 30 Jun 2023
Viewed by 894
Abstract
A comprehensive analysis of the intermolecular interaction energy and anharmonic vibrations of 41 structures of the HXeY⋯HX (X, Y = F, Cl, Br, I) family of noble-gas-compound complexes for all possible combinations of Y and X was conducted. New structures were identified, and [...] Read more.
A comprehensive analysis of the intermolecular interaction energy and anharmonic vibrations of 41 structures of the HXeY⋯HX (X, Y = F, Cl, Br, I) family of noble-gas-compound complexes for all possible combinations of Y and X was conducted. New structures were identified, and their interaction energies were studied by means of symmetry-adapted perturbation theory, up to second-order corrections: this provided insight into the physical nature of the interaction in the complexes. The energy components were discussed, in connection to anharmonic frequency analysis. The results show that the induction and dispersion corrections were the main driving forces of the interaction, and that their relative contributions correlated with the complexation effects seen in the vibrational stretching modes of Xe–H and H–X. Reasonably clear patterns of interaction were found for different structures. Our findings corroborate previous findings with better methods, and provide new data. These results suggest that the entire group of the studied complexes can be labelled as “naturally blueshifting”, except for the complexes with HI. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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20 pages, 2827 KiB  
Article
Fundamental Aspects of Skin Cancer Drugs via Degree-Based Chemical Bonding Topological Descriptors
by Abdul Rauf Khan, Nadeem ul Hassan Awan, Muhammad Usman Ghani, Sayed M. Eldin, Hanen Karamti, Ahmed H. Jawhari and Yousef E. Mukhrish
Molecules 2023, 28(9), 3684; https://doi.org/10.3390/molecules28093684 - 24 Apr 2023
Cited by 15 | Viewed by 1563
Abstract
Due to significant advancements being made in the field of drug design, the use of topological descriptors remains the primary approach. When combined with QSPR models, descriptors illustrate a molecule’s chemical properties numerically. Numbers relating to chemical composition topological indices are structures that [...] Read more.
Due to significant advancements being made in the field of drug design, the use of topological descriptors remains the primary approach. When combined with QSPR models, descriptors illustrate a molecule’s chemical properties numerically. Numbers relating to chemical composition topological indices are structures that link chemical composition to physical characteristics. This research concentrates on the analysis of curvilinear regression models and degree-based topological descriptors for thirteen skin cancer drugs. The physicochemical characteristics of the skin cancer drugs are examined while regression models are built for computed index values. An analysis is performed for several significant results based on the acquired data. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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12 pages, 4295 KiB  
Article
Substituent Effects in Tetrel Bonds Involving Aromatic Silane Derivatives: An ab initio Study
by Sergi Burguera, Antonio Frontera and Antonio Bauzá
Molecules 2023, 28(5), 2385; https://doi.org/10.3390/molecules28052385 - 5 Mar 2023
Viewed by 1340
Abstract
In this manuscript substituent effects in several silicon tetrel bonding (TtB) complexes were investigated at the RI-MP2/def2-TZVP level of theory. Particularly, we have analysed how the interaction energy is influenced by the electronic nature of the substituent in both donor and acceptor moieties. [...] Read more.
In this manuscript substituent effects in several silicon tetrel bonding (TtB) complexes were investigated at the RI-MP2/def2-TZVP level of theory. Particularly, we have analysed how the interaction energy is influenced by the electronic nature of the substituent in both donor and acceptor moieties. To achieve that, several tetrafluorophenyl silane derivatives have been substituted at the meta and para positions by several electron donating and electron withdrawing groups (EDG and EWG, respectively), such as –NH2, –OCH3, –CH3, –H, –CF3 and –CN substituents. As electron donor molecules, we have used a series of hydrogen cyanide derivatives using the same EDGs and EWGs. We have obtained the Hammett’s plots for different combinations of donors and acceptors and in all cases we have obtained good regression plots (interaction energies vs. Hammet’s σ parameter). In addition, we have used the electrostatic potential (ESP) surface analysis as well as the Bader’s theory of atoms in molecules (AIM) and noncovalent interaction plot (NCI plot) techniques to further characterize the TtBs studied herein. Finally, a Cambridge Structural Database (CSD) inspection was carried out, retrieving several structures where halogenated aromatic silanes participate in tetrel bonding interactions, being an additional stabilization force of their supramolecular architectures. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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12 pages, 8777 KiB  
Article
Unicorns, Rhinoceroses and Chemical Bonds
by Jordan Gribben, Timothy R. Wilson and Mark E. Eberhart
Molecules 2023, 28(4), 1746; https://doi.org/10.3390/molecules28041746 - 12 Feb 2023
Viewed by 1668
Abstract
The nascent field of computationally aided molecular design will be built around the ability to make computation useful to synthetic chemists who draw on their empirically based chemical intuition to synthesize new and useful molecules. This fact poses a dilemma, as much of [...] Read more.
The nascent field of computationally aided molecular design will be built around the ability to make computation useful to synthetic chemists who draw on their empirically based chemical intuition to synthesize new and useful molecules. This fact poses a dilemma, as much of existing chemical intuition is framed in the language of chemical bonds, which are pictured as possessing physical properties. Unfortunately, it has been posited that calculating these bond properties is impossible because chemical bonds do not exist. For much of the computationalchemistry community, bonds are seen as mythical—the unicorns of the chemical world. Here, we show that this is not the case. Using the same formalism and concepts that illuminated the atoms in molecules, we shine light on the bonds that connect them. The real space analogue of the chemical bond becomes the bond bundle in an extended quantum theory of atoms in molecules (QTAIM). We show that bond bundles possess all the properties typically associated with chemical bonds, including an energy and electron count. In addition, bond bundles are characterized by a number of nontraditional attributes, including, significantly, a boundary. We show, with examples drawn from solid state and molecular chemistry, that the calculated properties of bond bundles are consistent with those that nourish chemical intuition. We go further, however, and show that bond bundles provide new and quantifiable insights into the structure and properties of molecules and materials. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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8 pages, 1955 KiB  
Article
Trivalent Polyhedra as Duals of Borane Deltahedra: From Molecular Endohedral Germanium Clusters to the Smallest Fullerenes
by R. Bruce King
Molecules 2023, 28(2), 496; https://doi.org/10.3390/molecules28020496 - 4 Jan 2023
Viewed by 1219
Abstract
The duals of the most spherical closo borane deltahedra having from 6 to 16 vertices form a series of homologous spherical trivalent polyhedra with even numbers of vertices from 8 to 28. This series of homologous polyhedra is found in endohedral clusters of [...] Read more.
The duals of the most spherical closo borane deltahedra having from 6 to 16 vertices form a series of homologous spherical trivalent polyhedra with even numbers of vertices from 8 to 28. This series of homologous polyhedra is found in endohedral clusters of the group 14 atoms such as the endohedral germanium cluster anions [M@Ge10]3− (M = Co, Fe) and [Ru@Ge12]3− The next members of this series have been predicted to be the lowest energy structures of the endohedral silicon clusters Cr@Si14 and M@Si16 (M = Zr, Hf). The largest members of this series correspond to the smallest fullerene polyhedra found in the endohedral fullerenes M@C28 (M = Zr, Hf, Th, U). The duals of the oblate (flattened) ellipsoidal deltahedra found in the dirhenaboranes Cp*2Re2Bn−2Hn−2 (Cp* = η5-Me5C5; 8 ≤ n ≤ 12) are prolate (elongated) trivalent polyhedra as exemplified experimentally by the germanium cluster [Co2@Ge16]4− containing an endohedral Co2 unit. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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12 pages, 5815 KiB  
Article
Theoretical Investigation of Geometries and Bonding of Indium Hydrides in the In2Hx and In3Hy (x = 0–4,6; y = 0–5) Series
by Anton S. Pozdeev, Pavel Rublev, Steve Scheiner and Alexander I. Boldyrev
Molecules 2023, 28(1), 183; https://doi.org/10.3390/molecules28010183 - 26 Dec 2022
Cited by 5 | Viewed by 2194
Abstract
Boron hydrides have been an object of intensive theoretical and experimental investigation for many decades due to their unusual and somewhat unique bonding patterns. Despite boron being a neighboring element to carbon, boron hydrides almost always form non-classical structures with multi-center bonds. However, [...] Read more.
Boron hydrides have been an object of intensive theoretical and experimental investigation for many decades due to their unusual and somewhat unique bonding patterns. Despite boron being a neighboring element to carbon, boron hydrides almost always form non-classical structures with multi-center bonds. However, we expect indium to form its interesting molecules with non-classical patterns, though such molecules still need to be extensively studied theoretically. In this work, we investigated indium hydrides of In2Hx (x = 0–4,6) and In3Hy (y = 0–5) series via DFT and ab initio quantum chemistry methods, performing a global minimum search, chemical bonding analysis, and studies of their thermodynamical stability. We found that the bonding pattern of indium hydrides differs from the classical structures composed of 1c-2e lone pairs and 2c-2e bonds and the bonding pattern of earlier investigated boron hydrides of the BnHn+2 series. The studied stoichiometries are characterized by multi-center bonds, aromaticity, and the tendency for indium to preserve the 1c-2e lone pair. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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12 pages, 2583 KiB  
Article
Selenoxides as Excellent Chalcogen Bond Donors: Effect of Metal Coordination
by Sergi Burguera, Rosa M. Gomila, Antonio Bauzá and Antonio Frontera
Molecules 2022, 27(24), 8837; https://doi.org/10.3390/molecules27248837 - 13 Dec 2022
Cited by 2 | Viewed by 1289
Abstract
The chalcogen bond has been recently defined by the IUPAC as the attractive noncovalent interaction between any element of group 16 acting as an electrophile and any atom (or group of atoms) acting as a nucleophile. Commonly used chalcogen bond donor molecules are [...] Read more.
The chalcogen bond has been recently defined by the IUPAC as the attractive noncovalent interaction between any element of group 16 acting as an electrophile and any atom (or group of atoms) acting as a nucleophile. Commonly used chalcogen bond donor molecules are divalent selenium and tellurium derivatives that exhibit two σ-holes. In fact, the presence of two σ-hole confers to the chalcogen bonding additional possibilities with respect to the halogen bond, the most abundant σ-hole interaction. In this manuscript, we demonstrate that selenoxides are good candidates to be used as σ-hole donor molecules. Such molecules have not been analyzed before as chalcogen bond donors, as far as our knowledge extends. The σ-hole opposite to the Se=O bond is adequate for establishing strong and directional ChBs, as demonstrated herein using the Cambridge structural database (CSD) and density functional theory (DFT) calculations. Moreover, the effect of the metal coordination of the selenoxide to transition metals on the strength of the ChB interaction has been analyzed theoretically. The existence of the ChBs has been further supported by the quantum theory of atoms in molecules (QTAIM) and the noncovalent interaction plot (NCIPlot). Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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16 pages, 4715 KiB  
Article
Facile Synthesis of 5-Aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides via Suzuki Cross-Coupling Reactions, Their Electronic and Nonlinear Optical Properties through DFT Calculations
by Gulraiz Ahmad, Nasir Rasool, Adeel Mubarik, Ameer Fawad Zahoor, Muhammad Ali Hashmi, Muhammad Zubair, Muhammad Bilal, Mohamed Hussien, Muhammad Saeed Akhtar and Sajjad Haider
Molecules 2021, 26(23), 7309; https://doi.org/10.3390/molecules26237309 - 2 Dec 2021
Cited by 11 | Viewed by 2786
Abstract
Synthesis of 5-aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides (4a4n) by a Suzuki cross-coupling reaction of 5-bromo-N-(pyrazin-2-yl)thiophene-2-carboxamide (3) with various aryl/heteroaryl boronic acids/pinacol esters was observed in this article. The intermediate compound 3 was prepared by condensation of pyrazin-2-amine [...] Read more.
Synthesis of 5-aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides (4a4n) by a Suzuki cross-coupling reaction of 5-bromo-N-(pyrazin-2-yl)thiophene-2-carboxamide (3) with various aryl/heteroaryl boronic acids/pinacol esters was observed in this article. The intermediate compound 3 was prepared by condensation of pyrazin-2-amine (1) with 5-bromothiophene-2-carboxylic acid (2) mediated by TiCl4. The target pyrazine analogs (4a4n) were confirmed by NMR and mass spectrometry. In DFT calculation of target molecules, several reactivity parameters like FMOs (EHOMO, ELUMO), HOMO–LUMO energy gap, electron affinity (A), ionization energy (I), electrophilicity index (ω), chemical softness (σ) and chemical hardness (η) were considered and discussed. Effect of various substituents was observed on values of the HOMO–LUMO energy gap and hyperpolarizability. The p-electronic delocalization extended over pyrazine, benzene and thiophene was examined in studying the NLO behavior. The chemical shifts of 1H NMR of all the synthesized compounds 4a4n were calculated and compared with the experimental values. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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11 pages, 3891 KiB  
Article
Comparative Study of Phosgene Gas Sensing Using Carbon and Boron Nitride Nanomaterials—A DFT Approach
by Emmanuel Obroni Kweitsu, Stephen Kanga Armoo, Kwabena Kan-Dapaah, Eric Kwabena Kyeh Abavare, David Dodoo-Arhin and Abu Yaya
Molecules 2021, 26(1), 120; https://doi.org/10.3390/molecules26010120 - 29 Dec 2020
Cited by 15 | Viewed by 3460
Abstract
Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of [...] Read more.
Phosgene (COCl2), a valuable industrial compound, maybe a public safety and health risk due to potential abuse and possible accidental spillage. Conventional techniques suffer from issues related to procedural complexity and sensitivity. Therefore, there is a need for the development of simple and highly sensitive techniques that overcome these challenges. Recent advances in nanomaterials science offer the opportunity for the development of such techniques by exploiting the unique properties of these nanostructures. In this study, we investigated the potential of six types of nanomaterials: three carbon-based ([5,0] CNT, C60, C70) and three boron nitride-based (BNNT, BN60, BN70) for the detection of COCl2. The local density approximation (LDA) approach of the density functional theory (DFT) was used to estimate the adsorption characteristics and conductivities of these materials. The results show that the COCl2 molecule adsorbed spontaneously on the Fullerene or nanocages and endothermically on the pristine zigzag nanotubes. Using the magnitude of the bandgap modulation, the order of suitability of the different nanomaterials was established as follows: PBN60 (0.19%) < PC70 (1.39%) < PC60 (1.77%) < PBNNT (27.64%) < PCNT (65.29%) < PBN70 (134.12%). Since the desired criterion for the design of an electronic device is increased conductivity after adsorption due to the resulting low power consumption, PC60 was found to be most suitable because of its power consumption as it had the largest decrease of 1.77% of the bandgap. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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Review

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17 pages, 1648 KiB  
Review
On the Nature of the Partial Covalent Bond between Noble Gas Elements and Noble Metal Atoms
by Ranita Pal and Pratim Kumar Chattaraj
Molecules 2023, 28(7), 3253; https://doi.org/10.3390/molecules28073253 - 5 Apr 2023
Cited by 3 | Viewed by 2363
Abstract
This article provides a discussion on the nature of bonding between noble gases (Ng) and noble metals (M) from a quantum chemical perspective by investigating compounds such as NgMY (Y=CN, O, NO3, SO4, CO3), [NgM−(bipy)]+, NgMCCH, and [...] Read more.
This article provides a discussion on the nature of bonding between noble gases (Ng) and noble metals (M) from a quantum chemical perspective by investigating compounds such as NgMY (Y=CN, O, NO3, SO4, CO3), [NgM−(bipy)]+, NgMCCH, and MCCNgH complexes, where M=Cu, Ag, Au and Ng=Kr−Rn, with some complexes containing the lighter noble gas atoms as well. Despite having very low chemical reactivity, noble gases have been observed to form weak bonds with noble metals such as copper, gold, and silver. In this study, we explore the factors that contribute to this unusual bonding behavior, including the electronic structure of the atoms involved and the geometric configuration of the concerned fragments. We also investigate the metastable nature of the resulting complexes by studying the energetics of their possible dissociation and internal isomerization channels. The noble gas-binding ability of the bare metal cyanides are higher than most of their bromide counterparts, with CuCN and AgCN showing higher affinity than their chloride analogues as well. In contrast, the oxides seem to have lower binding power than their corresponding halides. In the oxide and the bipyridyl complexes, the Ng-binding ability follows the order Au > Cu > Ag. The dissociation energies calculated, considering the zero-point energy correction for possible dissociation channels, increase as we move down the noble gas group. The bond between the noble gases and the noble metals in the complexes are found to have comparable weightage of orbital and electrostatic interactions, suggestive of a partial covalent nature. The same is validated from the topological analysis of electron density. Full article
(This article belongs to the Special Issue Fundamental Aspects of Chemical Bonding)
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