scholarly journals Can lone pair-π and cation-π interactions coexist? A theoretical study

2011 ◽  
Vol 9 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Carolina Estarellas ◽  
Antonio Frontera ◽  
David Quiñonero ◽  
Pere Deyà
Keyword(s):  
Interaction Potential ◽  
Theoretical Study ◽  
Noncovalent Interactions ◽  
Lone Pair ◽  
Geometric Features ◽  
Aromatic Rings ◽  
Partition Scheme ◽  
Π Interactions ◽  
Cooperativity Effects ◽  
Structural Database

AbstractThe interplay between two important noncovalent interactions involving different aromatic rings is studied by means of ab initio calculations (MP2/6-31++G**) computing the non-additivity energies. In this study we demonstrate the existence of cooperativity effects when cation-π and lone pair-π interactions coexist in the same system. These effects are studied theoretically using energetic and geometric features of the complexes. In addition we use Bader’s theory of atoms-in-molecules and Molecular Interaction Potential with polarization (MIPp) partition scheme to characterize the interactions. Experimental evidence for this combination of interactions has been obtained from the Cambridge Structural Database.

Structural characterization and photochromic behaviour of a novel compound based on a π-acidic naphthalene diimide derivative and a double hydroxide-bridged dinuclear AlIII aqua ion cluster

2019 ◽  
Vol 75 (8) ◽  
pp. 1128-1133 ◽  
Author(s):  
Hua Ke ◽  
Jian-Zhen Liao ◽  
Can-Zhong Lu
Keyword(s):  
Self Assembly ◽  
Noncovalent Interactions ◽  
Lone Pair ◽  
X Ray Diffraction ◽  
Photochromic Properties ◽  
X Ray ◽  
Π Interactions ◽  
Naphthalene Diimide ◽  
Double Hydroxide ◽  
Ion Cluster

Noncovalent interactions, such as π–π stacking interactions, C—H...π interactions and hydrogen bonding, are important driving forces for self-assembly in the construction of functional supermolecules and materials, especially in multicomponent supramolecular systems. Herein, a novel compound based on a π-acidic naphthalene diimide derivative and a double hydroxide-bridged dinuclear Al3+ aqua ion cluster, namely bis[N,N′-bis(2-sulfonatoethyl)-1,4,5,8-naphthalene diimide] di-μ-hydroxido-bis[tetraaquaaluminium(III)] tetrahydrate, (C18H12N2O10S2)2[Al2(OH)2(H2O)8]·4H2O, was obtained using the above-mentioned common noncovalent interactions, as well as uncommon lone-pair–π interactions. Functional molecular modules were connected by these noncovalent interactions to generate obvious photochromic properties. The compound was prepared by the self-assembly of N,N′-bis(2-sulfoethyl)-1,4,5,8-naphthalene diimide and Al(NO3)3·9H2O under mixed solvothermal conditions, and was characterized in detail by single-crystal X-ray diffraction, powder X-ray diffraction and FT–IR spectroscopy. The thermal stability and photochromic properties were also investigated; furthermore, in-situ solid-state UV–Vis absorption spectroscopy and electron spin resonance (ESR) were used to clarify the photochromic mechanism.

Energetic Effects between Halogen Bonds and Anion-π or Lone Pair-π Interactions: A Theoretical Study

2012 ◽  
Vol 116 (10) ◽  
pp. 2591-2597 ◽  
Author(s):  
Yunxiang Lu ◽  
Yingtao Liu ◽  
Haiying Li ◽  
Xiang Zhu ◽  
Honglai Liu ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Lone Pair ◽  
Halogen Bonds ◽  
Π Interactions

scholarly journals On the Importance of σ–Hole Interactions in Crystal Structures

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1205
Author(s):  
Antonio Frontera ◽  
Antonio Bauzá
Keyword(s):  
Lewis Acids ◽  
Noncovalent Interactions ◽  
Noble Gas ◽  
Lone Pair ◽  
Halogen Bonding ◽  
Lewis Base ◽  
Model Systems ◽  
Aromatic Rings ◽  
Potential Surfaces ◽  
Dual Character

Elements from groups 14–18 and periods 3–6 commonly behave as Lewis acids, which are involved in directional noncovalent interactions (NCI) with electron-rich species (lone pair donors), π systems (aromatic rings, triple and double bonds) as well as nonnucleophilic anions (BF4−, PF6−, ClO4−, etc.). Moreover, elements of groups 15 to 17 are also able to act as Lewis bases (from one to three available lone pairs, respectively), thus presenting a dual character. These emerging NCIs where the main group element behaves as Lewis base, belong to the σ–hole family of interactions. Particularly (i) tetrel bonding for elements belonging to group 14, (ii) pnictogen bonding for group 15, (iii) chalcogen bonding for group 16, (iv) halogen bonding for group 17, and (v) noble gas bondings for group 18. In general, σ–hole interactions exhibit different features when moving along the same group (offering larger and more positive σ–holes) or the same row (presenting a different number of available σ–holes and directionality) of the periodic table. This is illustrated in this review by using several examples retrieved from the Cambridge Structural Database (CSD), especially focused on σ–hole interactions, complemented with molecular electrostatic potential surfaces of model systems.

Effect of delocalization of nonbonding electron density on the stability of the M–Ccarbene bond in main group metal-imidazol-2-ylidene complexes: a computational and structural database study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Samuel Tetteh ◽  
Albert Ofori
Keyword(s):  
Electron Density ◽  
Lone Pair ◽  
Main Group ◽  
Binding Energies ◽  
Electrostatic Model ◽  
Group Metal ◽  
Main Group Metal ◽  
Structural Database ◽  
The Stability ◽  
Lone Pair Electrons

Abstract The M–Ccarbene bond in metal (M) complexes involving the imidazol-2-ylidene (Im) ligand has largely been described using the σ-donor only model with donation of σ electrons from the sp-hybridized orbital of the carbene carbon into vacant orbitals on the metal centre. Analyses of the M–Ccarbene bond in a series of group IA, IIA and IIIA main group metal complexes show that the M-Im interactions are mostly electrostatic with the M–Ccarbene bond distances greater than the sum of the respective covalent radii. Estimation of the binding energies of a series of metal hydride/fluoride/chloride imidazol-2-ylidene complexes revealed that the stability of the M–Ccarbene bond in these complexes is not always commensurate with the σ-only electrostatic model. Further natural bond orbital (NBO) analyses at the DFT/B3LYP level of theory revealed substantial covalency in the M–Ccarbene bond with minor delocalization of electron density from the lone pair electrons on the halide ligands into antibonding molecular orbitals on the Im ligand. Calculation of the thermodynamic stability of the M–Ccarbene bond showed that these interactions are mostly endothermic in the gas phase with reduced entropies giving an overall ΔG > 0.

scholarly journals The Affinity of Carboplatin to B-Vitamins and Nucleobases

2021 ◽  
Vol 22 (7) ◽  
pp. 3634
Author(s):  
Beata Szefler ◽  
Przemysław Czeleń ◽  
Przemysław Krawczyk
Keyword(s):  
Vitamin B6 ◽  
Pyridoxal Phosphate ◽  
Antitumor Agents ◽  
Lone Pair ◽  
Chemical Compounds ◽  
Free Energies ◽  
Aromatic Rings ◽  
Anti Cancer ◽  
Potential Impact ◽  
Reactive Molecule

Platinum compounds have found wide application in the treatment of various types of cancer and carboplatin is one of the main platinum-based drugs used as antitumor agents. The anticancer activity of carboplatin arises from interacting with DNA and inducing programmed cell death. However, such interactions may occur with other chemical compounds, such as vitamins containing aromatic rings with lone-pair orbitals, which reduces the anti-cancer effect of carboplatin. The most important aspect of the conducted research was related to the evaluation of carboplatin affinity to vitamins from the B group and the potential impact of such interactions on the reduction of therapeutic capabilities of carboplatin in anticancer therapy. Realized computations, including estimation of Gibbs Free Energies, allowed for the identification of the most reactive molecule, namely vitamin B6 (pyridoxal phosphate). In this case, the computational estimations indicating carboplatin reactivity were confirmed by spectrophotometric measurements.

Through-Space Transmission of 19F-13C Coupling Via an Intermediate Bond. An Experimental and Theoretical Study

1987 ◽  
Vol 40 (12) ◽  
pp. 1923 ◽  
Author(s):  
ID Rae ◽  
ID Rae ◽  
A Staffa ◽  
A Staffa ◽  
AC Diz ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Lone Pair ◽  
Electron Excitation ◽  
Carbonyl Groups ◽  
Polarization Propagator ◽  
Close Proximity ◽  
Fermi Contact ◽  
Intramolecular Hydrogen ◽  
Intermediate Bond ◽  
Insight Into

In order to obtain a deeper insight into the title effect, several compounds with an F atom very close to a C-H of a nearby functional group were synthesized and the relevant couplings measured. The most conspicuous case was that of 8-fluoro-2-hydroxynaphthalene-1-carbaldehyde where a close proximity between the F and H atoms is the result of fluorine-oxygen repulsion and the formation of an intramolecular hydrogen bond between the hydroxyl and carbonyl groups. The experimental four-bond J(F,CHO) coupling is 26.2 Hz. A compound very similar to this one, but without the OH group, was chosen on which to perform a polarization propagator analysis of the through-space (TS) coupling pathways, at the RPA-INDO level. The expression for the TS coupling in terms of the projected polarization propagator and perturbators was numerically analysed. It is found that this coupling is completely dominated by a TS component of the Fermi contact (FC) term, the main features of which are: ( i ) It decays exponentially with the F-H distance; (ii) Its main contribution comes from an electron excitation involving the F lone-pair, the C-H bond of the CHO moiety and its corresponding antibonding orbital;(iii) The π-type lone-pair does not contribute to the TS coupling pathway of the FC term.

scholarly journals N′-(3-Hydroxybenzylidene)-4-methylbenzohydrazide

2012 ◽  
Vol 68 (6) ◽  
pp. o1816-o1816
Author(s):  
Ji-Lai Liu ◽  
Ming-Hui Sun ◽  
Jing-Jun Ma
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Crystal Packing ◽  
Aromatic Rings ◽  
Π Interactions ◽  
Compound C ◽  
Centroid Distance ◽  
Benzene Rings

The title compound, C15H14N2O2, was obtained from the reaction of 3-hydroxybenzaldhyde and 4-methylbenzohydrazide in methanol. In the molecule, the benzene rings form a dihedral angle of 2.9 (3)°. In the crystal, N—H...O and O—H...O hydrogen bonds link the molecules into layers parallel to (101). The crystal packing also exhibits π–π interactions between the aromatic rings [centroid–centroid distance = 3.686 (4) Å].

Sign in / Sign up

Export Citation Format

Share Document