Synthesis, X-ray Crystallography, Spectroscopic Characterizations, Density Functional Theory, and Hirshfeld Surface Analyses of a Novel (Carbonato) Picket Fence Iron(III) Complex.

An Fe(III)-carbonato six-coordinate picket fence porphyrin complex with the formula [K(2,2,2-crypt)][FeIII(TpivPP)(CO3)]·C6H5Cl·3H2O (I) has been synthesized and characterized by UV-Vis and FT-IR spectra. The structure of (carbonato)(α,α,α,α-tetrakis(o-pivalamidophenyl)porphinato)ferrate(III) was also established by XRD. The iron atom is hexa-coordinated by the four nitrogen atoms of the pyrrol rings and the two oxygen atoms of the CO32- group. Complex I, characterized as a ferric high-spin complex (S = 5/2), presented higher Fe-Np (2.105(6) Å) and Fe-PC (0.654(2) Å) distances. Both X-ray molecular structure and Hirshfeld surface analysis results show that the crystal packing of I is made by C-H⋯O and C-H⋯Cg weak intermolecular hydrogen interactions involving neighboring [FeIII(TpivPP)(CO3)]- ion complexes. Computational studies were carried out at DFT/B3LYP-D3/LanL2DZ to investigate the HOMO and LUMO molecular frontier orbitals and the reactivity within the studied compound. The stability of compound I was investigated by analyzing both intra- and inter-molecular interactions using the 2D and 3DHirshfeld surface (HS) analyses. Additionally, the frontier molecular orbital (FMO) calculations and the molecular electronic potential (MEP) analyses were conducted to determine the electron localizations, electrophilic, and nucleophilic regions, as well as charge transfer (ECT) within the studied system.

Linear and Nonlinear Optical Responses of Nitrobenzofurazan-Sulfide Derivatives: DFT-QTAIM Investigation on Twisted Intramolecular Charge Transfer.

In this study, we report on the green fluorescence exhibited by nitrobenzofurazan-sulfide derivatives (NBD-Si, i = 1-4). The optical responses of these studied compounds in a polar methanol solvent were simulated by the use of time-dependent density functional theory (TD-DFT) employing the Becke-3-Parameter-Lee-Yang-Parr (B3LYP) functional along with the 6-31G(d,p) basis set. The computed energy and oscillator strength (f) results complement the experimental results. The band gap was calculated as the difference between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO). Additionally, the density of states (DOS) was computed, providing a comprehensive understanding of the fundamental properties of these materials and further corroborating the experimental data. When the experimental data derived from ultraviolet/visible (UV/visible) and fluorescence spectroscopic techniques and those from simulated spectra are analyzed, the extracted values match up adequately. In addition, the NBD-sulfide compounds exhibit a large Stokes shift up to 85 nm in a polar methanol solvent. They are hypothesized to represent a novel paradigm of excited-state intramolecular charge transfer (ICT). To understand the intrinsic optical properties of NBD-Si materials, an ICT was identified, and its direction within the molecule was evaluated using the ratio of ßvect and ßtotal, values extracted from the computed nonlinear optical (NLO) properties. Moreover, the reduced density gradient (RDG)-based noncovalent interactions (NCIs) were employed to characterize the strength and type of NBD-Si interactions. Furthermore, noncovalent interactions were identified and categorized using the Quantum Theory of Atoms in Molecules (QTAIM) analysis. Ultimately, the combination of Hirshfeld surface analysis and DFT calculations was utilized to enhance the characterization and rationalization of these NCIs.

Supramolecular clumps of µ2-1,3-acetate bridges of Cd(II)-Salen complex: Synthesis, spectroscopic characterization, crystal structure, DFT quantization's, and antifungal photodynamic therapy.

The article divulges the crystal growth, synthesis, and X-ray structure characterization of one centrosymmetric cadmium complex, [Cd{CdL(µ2-1,3-acetate)}2] using Salen ligand (SL). The complex is further characterized using spectroscopic and analytical techniques, including DRS, SEM-EDX, PXRD, and ICP-MS. The crystallographic study showed that the complex has a monoclinic space P21/c. Addison parameters (Æ®) show the hexagonal geometry of the central Cd(II) metal ion. Hirshfeld surface and 2-D fingerprint confirm supramolecular contacts despite weak C-H⋯O and C-H···π interactions. Energy frameworks, FMOs, global reactivity parameters, MEP, and energy bandgap explain the complex reactivity outlook. The complex inter- and intramolecular bonding interactions were explored through natural bond orbital (NBO), QTAIM, NCI-RDG, Electron Location Function (ELF), and Localized Orbital Locator (LOL) quantization methods. In addition, the complex and its synthetic components in vitro antibacterial efficacy were investigated using Gram-positive and Gram-negative microbial strains. SAR (structure-activity relationship) correlates with biological potency. Molecular docking assessed antimicrobial potency with proteins S. aureus (PDB ID: 1JIJ), C. albicans (PDB ID: 1M7A), E. coli (PDB ID: 1T9U), P. aeruginosa (PDB ID: 2UV0), and A. Niger (PDB ID: 3K4P). The findings are backed by the Protein-Ligand Interaction Profiler (PLIP). The antifungal potency and cell viability test of C. albicans were conducted using photodynamic therapy (APDT).

Synthesis, characterization, crystal structure, and fabrication of photosensitive Schottky device of a binuclear Cu(ii)-Salen complex: a DFT investigations.

This work explores one centrosymmetric binuclear Cu(ii)-Salen complex synthesis, characterization, photosensitive Schottky barrier diode (PSBD) function, and DFT spectrum. The crystal growth involves H2LSAL and Cu(NO3)2·3H2O in CH3OH + ACN (acetonitrile) solvent medium. Herein, structural characterization employs elemental, IR/Raman, NMR, UV-VIS, DRS, SEM-EDX, PXRD, SCXRD, and XPS analyses. The complex crystal size is 0.2 × 0.2 × 0.2, showing monoclinic space group C2/c. The dimeric unit contains two Cu(ii) centres with distorted square pyramidal (SQP) geometries. The crystal packing consists of weak C-H⋯O interactions. DFT and Hirshfeld surface (HS) further substantiated the packing interactions, providing valuable insights into the underlying mechanisms. The 2-D fingerprint plots showed the presence of N⋯H (3%) and O⋯H (8.2%) contacts in the molecular arrangement. NBO, QTAIM, ELF-LOL, and energy frameworks are utilized to investigate the bonding features of the complex. We extensively studied electrical conductivity and PSBD for H2LSAL and the complex based on band gap (3.09 and 3.07 eV). Like an SBD, the complex has better electrical conductivity, evidencing potentiality in optoelectronic device applications. Optical response enhances conductivity, according to I-V characteristics. Complex Schottky diode has lower barrier height, resistance, and higher conductivity under light. The complex transports charge carriers through space and is rationalized by the 'hopping process' and 'structure-activity-relationship' (SAR). The charge transport mechanism was analysed by estimating complex mobility (µeff), lifetime (τ), and diffusion length (LD). The experimental and theoretical DOS/PDOS plots provide evidence for the Schottky diode function of the complex.

DFT-Computational Modeling and TiberCAD Frameworks for Photovoltaic Performance Investigation of Copper-Based 2D Hybrid Perovskite Solar Absorbers.

In this work, we use a combination of dispersion-corrected density functional theory (DFT-D3) and the TiberCAD framework for the first time to investigate a newly designed and synthesized class of (C6H10N2)[CuCl4] 2D-type perovskite. The inter- and intra-atomic reorganization in the crystal packing and the type of interaction forming in the active area have been discussed via Hirshfeld surface (HS) analyses. A distinct charge transfer from CuCl4 to [C6H10N2] is identified by frontier molecular orbitals (FMOs) and density of states (DOS). This newly designed narrow-band gap small-molecule perovskite, with an energy gap (E g) of 2.11 eV, exhibits a higher fill factor (FF = 81.34%), leading to an open-circuit voltage (V oc) of 1.738 V and a power conversion efficiency (PCE) approaching ∼10.20%. The interaction between a donor (D) and an acceptor (A) results in a charge transfer complex (CT) through the formation of hydrogen bonds (Cl-H), as revealed by QTAIM analysis. These findings were further supported by 2D-LOL and 3D-ELF analyses by visualizing excess electrons surrounding the acceptor entity. Finally, we performed numerical simulations of solar cell structures using TiberCAD software.

Exploring Nano-optical Molecular Switch Systems for Potential Electronic Devices: Understanding Electric and Electronic Properties through DFT-QTAIM Assembly.

The design and synthesis of molecular nanoswitches using organic molecules represent a crucial research field within molecular electronics. To understand the switching mechanisms, it is essential to investigate various factors, such as charge/energy transfer, electron transfer, nonlinear optical properties (NLO), current-voltage (I-V) curves, Joule-like (LJL) and Peltier-like (LPL) intramolecular phenomenological coefficients, as well as the energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) boundary orbitals. In this Article, a novel approach to designing a molecular nanoswitch and understanding its ON/OFF mechanism is presented, utilizing the quantum theory of atoms in molecules (QTAIM), density functional theory (DFT), and Landauer theory (LT). These analyses contribute significantly to a deep understanding of switching effects within molecular electronic systems.

Design, Transport/Molecular Scale Electronics, Electric Properties, and a Conventional Quantum Study of a New Potential Molecular Switch for Nanoelectronic Devices.

In this study, we examined the influence of an external electric field applied in two directions: horizontal (X-axis) and vertical (Y-axis) on the electronic and vibrational properties of a field-effect molecular switch, denoted as M. We employed density functional theory and quantum theory of atoms in molecules for this analysis. The current-voltage (I-V) characteristic curve of molecular switch system M was computed by applying the Landauer formula. The results showed that the switching mechanism depends on the direction of the electric field. When the electric field is applied along the X-axis and its intensity is around 0.01 au, OFF/ON switching mechanisms occur. By utilizing electronic localization functions and localized-orbital locator topological analysis, we observed significant intramolecular electronic charge transfer "back and forth" in Au-M-Au systems when compared to the isolated system. The noncovalent interaction revealed that the Au-M-Au complex is also stabilized by electrostatic interactions. However, if the electric field is applied along the Y-axis, a switching mechanism (OFF/ON) occurs when the electric field intensity reaches 0.008 au. Additionally, the local electronic phenomenological coefficients (Lelec) of this field-effect molecular switch were determined by using the Onsager phenomenological approach. It can also be predicted that the molecular electrical conductance (G) increases as Lelec increases. Finally, the electronic and vibrational properties of the proposed models M and Au-M-Au exhibit a powerful switching mechanism that may potentially be employed in a new generation of electronic devices.

A theoretical and electrochemical impedance spectroscopy study of the adsorption and sensing of selected metal ions by 4-morpholino-7-nitrobenzofuran.

The selectivity of a novel chemosensor, based on a modified nitrobenzofurazan referred to as NBD-Morph, has been investigated for the detection of heavy metal cations (Co2+, Pb2+, Mg2+, Ag+, Cu2+, Hg2+, Ni2+, and Zn2+). The ligand, 4-morpholino-7-nitrobenzofurazan (NBD-Morph), was characterized using spectroscopic techniques including FT-IR and 1H NMR. Vibrational frequencies obtained from FT-IR and proton NMR (1H) chemical shifts were accurately predicted employing the density functional theory (DFT) at the B3LYP level of theory. Furthermore, an examination of the structural, electronic, and quantum chemical properties was conducted and discussed. DFT calculations were employed to explore the complex formation ability of the NBD-Morph ligand with Co2+, Pb2+, Mg2+, Ag+, Cu2+, Hg2+, Ni2+, and Zn2+ metal cations. The comparison of adsorption energies for all possible conformations reveals that NBD-Morph exhibits sensitivity and selectivity towards metal ions, including Pb2+, Cu2+, Ag+, and Ni2+. However, an assessment of their reactivity using QTAIM topological parameters demonstrated the ligand's greater complexation ability toward Cu2+ or Ni2+ than those formed by Pb2+ or Ag+. Additionally, molecular electrostatic potential (MEP), Hirshfeld surfaces, and their associated 2D-fingerprint plots were applied to a detailed study of the inter-molecular interactions in NBD-Morph-X (X = Pb2+, Cu2+, Ag+, Ni2+) complexes. The electron localization function (ELF) and the localized-orbital locator (LOL) were generated to investigate the charge transfer and donor-acceptor interactions within the complexes. Electrochemical analysis further corroborates the theoretical findings, supporting the prediction of NBD-Morph's sensory ability towards Ni2+ metal cations. In conclusion, NBD-Morph stands out as a promising sensor for Ni2+.

Exploration of intramolecular charge transfer in para-substituted nitrobenzofurazan: Experimental and theoretical analyses.

The present work aims at exploring the high electrophilic character of 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) toward the morpholine group by an SNAr reaction in acetonitrile or water (thereafter referred to as NBD-Morph). The electron-donating ability of the morpholine causes intra-molecular charge transfer (ICT). In this report, we present a comprehensive study on the optical characteristics using UV-Vis, photoluminescence (cw-PL) and its time-resolved (TR-PL) to determine the properties of the emissive intramolecular charge transfer (ICT) in the NBD-Morph donor-acceptor system. An exhaustive theoretical investigation utilizing the density functional theory (DFT) and its extension TD-DFT methods is an essential complement of experiments to rationalize and understand the molecular structure and related properties. The findings from QTAIM, ELF, and RDG analyses establish that the bonding between morpholine and NBD moieties is of the electrostatic or hydrogen bond type. In addition, the Hirshfeld surfaces have been established to explore the types of interactions. Further, the non-linear optical (NLO) responses of the compound have been examined. The structure-property relationships obtained through the combined experimental and theoretical offer valuable insights for designing efficient NLO material.

Host-guest complexation studies of NO3, NO2, CO2, and N2 gas with the calix[4]arene molecule.

Calix[n]arenes (abbreviated as CX[n]) are the macro-molecules based on phenol groups with a hydrophobic cavity to encapsulate a gas or small molecules. They are used as molecular vehicles. For instance, these molecules are used in the activation of the solubility of monomers in the specific media and in pharmaceutical drug delivery. The limit of the development of gaseous pollutants will be a vital subject in the future. The polluting gases NO3, NO2, CO2, N2, etc., need cage molecules, such as CX[4], to be encapsulated. In this report, the red shift of the H-bonding interactions of the CX[4]-gas (by adding the gas inside or outside the cavity) is clearly explained by the vibrational analysis. The electronic spectra of the complexes of CX[4] with NO3, NO2, CO2, and N2) exhibit a blue-shift pick in comparison with the ones observed for the CX[4] molecule. The electrophilic and nucleophilic sites of the stable host-guest have been investigated. Additionally, the non-covalent interactions have been calculated based on the reduced density gradient RDG and QTAIM theory.

Role of hydrogen bonding interactions within of the conformational preferences of calix[n = 4,6,8]arene: DFT and QTAIM analysis.

Understanding the interactions of the cage molecules with a variety of invited molecules is getting very important. But, the hydrogen bonds can also play a crucial role in the interaction phenomenon. In this work, natural population analysis (NPA), chemical shifts, and atom in molecules (AIM) analysis have been used to identify the role of hydrogen bonds in the stability of CX[n] molecules. According to our calculation, the 13C NMR spectra are also sensitive to the nature of hydrogen bonds. We note that the DFT calculations have reproduced with a very good agreement, the experimentally observed chemical shifts of CX[4].

New zinc phthalocyanine derivatives for nitrogen dioxide sensors: A theoretical optoelectronic investigation.

Zinc-phthalocyanines ZnPc derivatives including quinoleinoxy groups have been studied through DFT calculations. The most stable geometries were characterized for the unsubstituted to the tetra substituted ZnPcs. The energy gap decreased from 2.146 eV for ZnPc to 2.050 eV for ZnPcR4, in agreement with the experimental trend, and indicating the reliability of the electrochemical evaluation of LUMO and HOMO energy levels. Optical transitions computed at the CAM-B3LYP-D3 with triple zeta basis sets were found to be in good agreement with experimental values for both the B and Q bands. Subsequently, structures were also characterized for NO2 adsorbed complexes, in order to assess the potential role of ZnPc as a NO2 sensor. A clear sigma bonding chemisorption of NO2 on Zn atom is observed for all derivatives, followed by a charge transfer from the π Pc conjugated system to the Zn-NO2 moiety. More importantly, after NO2 chemisorption on ZnPc derivative a remarkable red-shift is observed in the optical spectra, particularly for NO2/ZnPcR4 complex, thus offering a good index to detect the binding of NO2. The optical spectra and the vibrational spectra can therefore be used to detect the presence of NO2 and ZnPc derivatives show appropriate properties to constitute good NO2 sensors.