Geometries and properties of excited states in the gas phase and in solution: theory and application of a time-dependent density functional theory polarizable continuum model

Metal complexes of benzimidazole-derived as potential anti-cancer agents: synthesis, characterization, combined experimental and computational studies

In this study, a series of 14 Cu (II), Zn (II), Ni (II) and Ag (I) complexes containing bis-benzimidazole derivatives were successfully designed and synthesized from 2-(1H-benzimidazole-2-yl)-phenol derivatives and corresponding metal salt solutions. The compound structures were identified by FT-IR, ¹H-NMR, powder X-ray diffraction and ESI-MS analyses, and the presence of the metal in the complexes was confirmed by ultraviolet-visible spectroscopy and ICP optical emission spectrometry. Electronic structure calculations were also carried out to describe the detailed structures in addition to the electronic absorption spectra of the ligands. The cytotoxic activity of the complexes was evaluated against three human cancer cell lines: lung (A549), breast (MDA-MB-231) and prostate (PC3) cancer cells. All complexes inhibited anti-proliferative cancer cells better than free ligands, especially Zn (II) and Ag (I) complexes, which are most sensitive to MDA-MB-231 cells. In addition, showing the growth inhibition of three cancer cell lines with IC₅₀ < 10.4 µM, complexes C₁ , C₃ and C₁₄ could be considered potential multi-targeted anti-cancer agents.

Metal complexes of benzimidazole-derived as potential anti-cancer agents: synthesis, characterization, combined experimental and computational studies

In this study, a series of 14 Cu (II), Zn (II), Ni (II) and Ag (I) complexes containing bis-benzimidazole derivatives were successfully designed and synthesized from 2-(1H-benzimidazole-2-yl)-phenol derivatives and corresponding metal salt solutions. The compound structures were identified by FT-IR, ¹H-NMR, powder X-ray diffraction and ESI-MS analyses, and the presence of the metal in the complexes was confirmed by ultraviolet-visible spectroscopy and ICP optical emission spectrometry. Electronic structure calculations were also carried out to describe the detailed structures in addition to the electronic absorption spectra of the ligands. The cytotoxic activity of the complexes was evaluated against three human cancer cell lines: lung (A549), breast (MDA-MB-231) and prostate (PC3) cancer cells. All complexes inhibited anti-proliferative cancer cells better than free ligands, especially Zn (II) and Ag (I) complexes, which are most sensitive to MDA-MB-231 cells. In addition, showing the growth inhibition of three cancer cell lines with IC₅₀ < 10.4 µM, complexes C₁ , C₃ and C₁₄ could be considered potential multi-targeted anti-cancer agents.

Coupling between Plasmonic and Molecular Excitations: TDDFT Investigation of an Ag-Nanorod/BODIPY-Dye Interaction

A time-dependent density functional theory (TDDFT) computational approach is employed to study the optical coupling between a plasmonic system (a Ag₅₀ nanorod) and a fluorescent dye (BODIPY). It is found that the BODIPY dye can interact with a plasmonic system in a rather different and selective way according to the mutual orientation of the fragments. Indeed, (i) the plasmon excitation turns out to be sensitive to the presence of the BODIPY transition and (ii) this can lead to amplify or suppress the resonance accordingly to the relative orientation of the corresponding transition dipoles. To understand the coupling mechanism, we analyze the shape of the induced density in real space and the Individual Component Map of the Oscillator Strength (ICM-OS) plots and achieve a simple rationalization and insight on the origin and features of the coupling. The resulting possibility of understanding plasmon/fluorophore interactions by simple qualitative arguments opens the way to a rational design of hybrid (plasmon + dye) systems with the desired optical behavior.

Ultrasensitive and rapid colorimetric detection of urotropin boosted by effective electrostatic probing and non-covalent sampling

Leakage and contamination of hazardous chemical substances have been widely recognized as the critical issue in ensuring human health, maintaining environmental sustainability, and safeguarding public security. Urotropin as a crucial raw material in industrial holds a potential threat to aquatic/atmospheric environment with refractory degradation problem, hence, there remains a severe challenge to effectively and on-site monitor urotropin. Here, a general design with all-in-one strategy was presented, in which a highly integrated "pocket sensing chip" combining a sampling unit and a detecting unit together endows a rapid and ultrasensitive colorimetric detection without dead-zone towards urotropin. By loading fast blue B as sensing reagent in the detecting unit, a moderate and sensitive detection towards urotropin via electrostatic interaction was achieved with detection limits of 9 μM for liquid and 17.19 ng for particulates. Furthermore, an expandable sensing chip for the purpose of simultaneously screening on multi-target exhibited remarkable applicability for examining suspicious objects with all sorts of surface in real scenes, being unacted on environmental complexity. We expect this design would provide a universal strategy and the high referential value to propel the development of handy and portable sensing device to efficiently screen the environmental relevant critical substance on-site.

Conformationally Confined Emissive Cationic Macrocycle with Photocontrolled Organelle-Specific Translocation

The optimization of molecular conformation and aggregation modes is of great significance in creation of new luminescent materials for biochemical research and medical diagnostics. Herein, a highly emissive macrocycle (1) is reported, which is constructed by the cyclization reaction of triphenylamine with benzyl bromide and exhibits very distinctive photophysical performance both in aqueous solution and the solid state. Structural analysis reveals that the 1 can form self-interpenetrated complex and emit bright yellow fluorescence in the crystal lattice. The distorted yet symmetrical structure can endow 1 with unique two-photon absorption property upon excitation by near-infrared light. Also, 1 can be utilized as an efficient photosensitizer to produce singlet oxygen (1 O2 ) both in inanimate milieu and under cellular environment. More intriguingly, due to the strong association of 1 with negatively charged biomacromolecules, organelle-specific migration is achieved from lysosome to nucleus during the 1 O2 -induced cell apoptosis process. To be envisaged, this conformationally confined cationic macrocycle with photocontrolled lysosome-to-nucleus translocation may provide a feasible approach for in situ identifying different biospecies and monitoring physiological events at subcellular level.

A combined study on structures and vibrational spectra of the antiviral rimantadine using SQMFF and DFT calculations

In this research, a combined study on structures and vibrational spectra of antiviral rimantadine have been performed using hybrid B3LYP/6-311++G∗∗ calculations and the scaled quantum force field (SQMFF) procedure. Harmonic force fields and scaled force constants of Free Base (FB), Cationic (CA) and Hydrochloride (HCl) species derived from the antiviral rimantadine have been calculated in gas phase and in aqueous solution using normal internal coordinates and scaling factors. Good correlations were acquired comparing the theoretical IR, Raman, 1H- 13C-NMR and UV spectra of three species with the analogous experimental ones, suggesting probably, the presence of all them in both phases. The main force constants of three species have evidenced lower values than the corresponding to antiviral amantadine. The ionic character of N1-H33⋯Cl36 bond of HCl species in aqueous solution evidence positive Mulliken charge on N1 atom indicating that this species is as CA one. Rimantadine presents higher solvation energies in water than other antiviral species, such as chloroquin, niclosamide, cidofovir and brincidofovir. The FB and HCl species of rimantadine are slightly less reactive than the corresponding to amantadine while the opposite is observed for the CA species. The predicted ECD spectra for the FB and CA species show positive Cotton effect different from the negative observed for the HCl one. These different behaviours of three species of rimantadine could probably explain the differences observed in the intensities of bands predicted in the electronic spectra of these species.

Dithiocarbazate Ligand-Based Cu(II), Ni(II), and Zn(II) Complexes: Synthesis, Structural Investigations, Cytotoxicity, DNA Binding, and Molecular Docking Studies

S-4-methylbenzyl-β-N-(2-methoxybenzylmethylene)dithiocarbazate ligand, 1, prepared from S-(4-methylbenzyl)dithiocarbazate, was used to produce a novel series of transition metal complexes of the type, [M (L)₂] [M = Cu(II) (2), Ni(II) (3), and Zn(II) (4), L = 1]. The ligand and its complexes were investigated by elemental analysis, FTIR, ¹H and ¹³C-NMR, MS spectrometry, and molar conductivity. In addition, single X-ray crystallography was also performed for ligand, 1, and complex 3. The Hirshfeld surface analyses were also performed to know about various bonding interactions in the ligand, 1, and complex 3. The investigated compounds were also tested to evaluate their cytotoxic behaviour. However, complex 2 showed promising results against MCF-7 and MDA-MB-213 cancer cell lines. Furthermore, the interaction of CT-DNA with ligand, 1, and complex 2 was also studied using the electronic absorption method, revealing that the compounds have potential DNA-binding ability via hydrogen bonding and hydrophobic and van der Waals interactions. A molecular docking study of complex 2 was also carried out, which revealed that free binding free energy value was −7.39 kcal mol⁻¹.

Synthesis, Crystal Structures, and Density Functional Theory Studies of Two Salt Cocrystals Containing Meldrum's Acid Group

Two salt cocrystals, C₃₁H₃₄N₄O₈ (DDD) and C₁₇H₂₀N₂O₈ (MDD), were synthesized and their structures were determined by single-crystal X-ray diffraction. DDD is made up of one (C₁₃H₁₃O₈)^- anion, one (C₉H₁₁N₂)⁺ cation, and one 5,6-dimethyl-1H-benzo[d]imidazole molecule. MDD consists of one (C₄H₇N₂)⁺ cation and one (C₁₃H₁₃O₈)^- anion. DDD and MDD belong to the monoclinic, P21/c space group and triclinic, P-1 space group, respectively. A 1D-chained structure of DDD was constituted by N-H···N and N-H···O hydrogen bonds. However, a 1D-chained structure of MDD was bridged by N-H···O hydrogen bonds. Their density functional theory-optimized geometric structures with a B3LYP/6-311G(d,p) basis set fit well with those of crystallographic studies. By calculating their thermodynamic properties, the correlation equations of C ⁰ _p,m , S ⁰ _m , H ⁰ _m , and temperature T were obtained. By comparing the experimental electronic spectra with the calculated electronic spectra, it is found that the PBEPBE/6-311G(d,p) method can simulate the UV-Vis spectra of DDD and MDD. In addition, the fluorescence spectra in the EtOH solution analysis show that the yellowish-green emission occurs at 570 nm (λ_ex = 310 nm) for DDD and the purplish-blue emission occurs at 454 nm (λ_ex = 316 nm) for MDD.

D-π-A Dual-Mode Probe Design for the Detection of nM-Level Typical Oxidants

Although a set of functional molecules with the D-π-A structure has been explored as optical probes for the detection of target analytes, it remains a great challenge to elaborately design a single probe for distinguishing different analytes by their intrinsic oxidation or reduction capabilities and thus to generate distinct optical responses. Here, a unique TCF-based probe (DMA-CN) containing two unsaturated double bonds in the π-conjugation bridge and TCF with different reaction activities that could be cut off by KMnO₄ and NaClO in varying degrees was developed, causing remarkably distinguishable responses for both fluorescence and colorimetric channels to discriminate KMnO₄ and NaClO from each other. The fluorescence and colorimetric limits of detection (LODs) of the proposed DMA-CN toward KMnO₄ were calculated as 60 and 91 nM, respectively, while those for NaClO were 13.3 and 214 nM, and all the optical signal change can be observed within 1 s with good specificity. Based on the proposed probe design strategy, a well-fabricated test strip was proven to be promising for the rapid, in-field detection and risk management. We expect that the present probe design methodology would provide a powerful strategy for efficient probe exploration, especially for discriminating the substances with similar oxidizing properties.

Acriflavine in aqueous solution: excitation and hydration

Using TD-DFT/DFT, the ground and excited states of the acriflavine dye were studied in an aqueous medium. The mutual influence of photoexcitation and strong hydrogen bonds with the solvent was studied by comparing the purely implicit and combined modeling of the aqueous environment of the dye. The excitation of acriflavine was calculated considering the vibronic coupling. The effect of photoexcitation on dye vibrations was analyzed. The spatial structure of the acriflavine H-dimer was obtained and its absorption was estimated.

Evaluation of molecular photophysical and photochemical properties using linear response time-dependent density functional theory with classical embedding: Successes and challenges

Time-dependent density functional theory (TDDFT) based approaches have been developed in recent years to model the excited-state properties and transition processes of the molecules in the gas-phase and in a condensed medium, such as in a solution and protein microenvironment or near semiconductor and metal surfaces. In the latter case, usually, classical embedding models have been adopted to account for the molecular environmental effects, leading to the multi-scale approaches of TDDFT/polarizable continuum model (PCM) and TDDFT/molecular mechanics (MM), where a molecular system of interest is designated as the quantum mechanical region and treated with TDDFT, while the environment is usually described using either a PCM or (non-polarizable or polarizable) MM force fields. In this Perspective, we briefly review these TDDFT-related multi-scale models with a specific emphasis on the implementation of analytical energy derivatives, such as the energy gradient and Hessian, the nonadiabatic coupling, the spin-orbit coupling, and the transition dipole moment as well as their nuclear derivatives for various radiative and radiativeless transition processes among electronic states. Three variations of the TDDFT method, the Tamm-Dancoff approximation to TDDFT, spin-flip DFT, and spin-adiabatic TDDFT, are discussed. Moreover, using a model system (pyridine-Ag20 complex), we emphasize that caution is needed to properly account for system-environment interactions within the TDDFT/MM models. Specifically, one should appropriately damp the electrostatic embedding potential from MM atoms and carefully tune the van der Waals interaction potential between the system and the environment. We also highlight the lack of proper treatment of charge transfer between the quantum mechanics and MM regions as well as the need for accelerated TDDFT modelings and interpretability, which calls for new method developments.

Electronic Structure of de Novo Peptide ACC-Hex from First Principles

Proteins are promising components for bioelectronic devices due in part to their biocompatibility, flexibility, and chemical diversity, which enable tuning of material properties. Indeed, an increasingly broad range of conductive protein supramolecular materials have been reported. However, due to their structural and environmental complexity, the electronic structure, and hence conductivity, of protein assemblies is not well-understood. Here we perform an all-atom simulation of the physical and electronic structure of a recently synthesized self-assembled peptide antiparallel coiled-coil hexamer, ACC-Hex. Using classical molecular dynamics and first-principles density functional theory, we examine the interactions of each peptide, containing phenylalanine residues along a hydrophobic core, to form a hexamer structure. We find that while frontier electronic orbitals are composed of phenylalanine, the peptide backbone and remaining residues, including those influenced by solvent, also contribute to the electronic density. Additionally, by studying dimers extracted from the hexamer, we show that structural distortions due to atomic fluctuations significantly impact the electronic structure of the peptide bundle. These results indicate that it is necessary to consider the full atomistic picture when using the electronic structure of supramolecular protein complexes to predict electronic properties.

A Computational Study on the Photochemical O-H Functionalization of Alcohols with Diazoacetates

In this computational study, we provide a detailed analysis of the underlying reaction mechanism and show that a singlet carbene is initially formed. Depending on the pK_A of the alcohol, this singlet carbene can engage in direct protonation or enol formation to yield the O-H functionalization product. On the contrary, propargylic alcohols take up a dual role and form a complex with the carbene intermediate that leads to facile cyclopropenation reactions.

Coumarin 343 in aqueous solution: theoretical analysis of absorption

Vibronic coupling and hydration were taken into account when describing the absorption of coumarin C343 (both neutral and anionic forms) in an aqueous media. It was shown that the B3LYP functional with the 6-31 +  + G(d,p) basis set and the IEFPCM solvent continuum model give theoretical vibronic absorption spectra, which are coincide with the experimental ones. Of the structural differences between C343⁰ and C343^-, there is a different twisting of the carboxyl group additionally changing due to excitation. Upon excitation, a significant shift in the electron density occurs from the C10 atom to the C4 atom only. Thus, a charge transfer on the scale of the entire molecule does not occur. Different hydration complexes with strongly bound water molecules have been analyzed.

Polarity and strong sensitivity to external electric field in azacrown oligophenylenevinylene

Complex study of quadrupolar azacrown dye (E,E)-5,5́-Bis[2-(4-(4',7',10',13',16'-pentaoxa-1 azacyclooctadecyl)phenyl)ethenyl]-2,2́-bipyridine 1 was performed. Electronic spectra of absorption and fluorescence in different solvents exhibit strong solvatochromism. Electrooptical absorption measurements (EOAM) were performed to determine the electric dipole moments. These measurements gave large values of dipole moments in the ground μ_g and Franck-Condon excited state μ_e^FC equal to 6.8 ± 0.14C m and 39.3 ± 0.3C m, respectively. Furthermore, the results of EOAM suggest the existence two conformers in the ground state with close energies of electronic transitions. Density functional theory (DFT) calculations directly show that the shape of this molecule is not planar in the ground state and also allows the existence of two stable conformers with close energies. They appeared due to different orientations of the left and right pyridine fragments of the solute. The energies, electric dipole moments and dependences of dipole moments on the strength of applied electric field were calculated for found stable conformers of 1. DFT calculations with TD / B3LYP / 3-21G and cc-pVDZ (Time Depend) approach show that external electric field increases dramatically the dipole moments of the solute under study. The higher field intensity the larger the excited electric dipole in the range intensities from zero to ∼ 2.8·× 10 ⁹ V/m.

Metalloceneincorporated Hybrid Singly N-Methyl N-Confused Calixphyrins: Synthesis, Characterization, Protonation and Deprotonation Studies

Rational design and isolation of two hitherto unknown highly stable single conformer of ferrocene incorporated meso-aryl substituted singly N-methyl N-confused-calixphyrins have been achieved in quantitative yields. The solid-state crystal structure reveals the obvious trans-geometry for the meso-protons with the possibility for both the macrocycles to exist either racemic or enantiomer forms. However, thorough solution-state spectroscopic characterization strongly concludes the experimental isolation of a single isomer for both the macrocycles. The drastic modification of UV-vis spectral patterns upon imine pyrrole N protonation and amine pyrrole NH deprotonation of both the calixphyrins could pave way for these macrocycles to act as opto-electronic materials. The conformational preorganization and protonation and deprotonation induced conformational reorganization have been extensively studied by solution state spectroscopic techniques, solid state X-ray crystal structure and in depth DFT level theoretical calculations.

Induced Near-Infrared Emission and Controlled Photooxidation based on Sulfonated Crown Ether in Water

Regulation of physio-chemical properties and reaction activities via noncovalent methodology has become one of increasingly significant topics in supramolecular chemistry and showed inventive applications in miscellaneous fields. Herein, we demonstrate that sulfonated crown ether can form very stable host-guest complexes with a series of push-pull-type photosensitizers, eventually leading to the dramatic fluorescence enhancement in visible and near-infrared regions. Meanwhile, severe suppression in singlet oxygen (¹ O₂ ) production is found, mainly due to the higher energy barriers between the excited single and triple states upon host-guest complexation. Moreover, such complexation-induced tuneable ¹ O₂ generation systems has been utilized in adjusting the photochemical oxidation reactions of polycyclic aromatic hydrocarbons (anthracene) and sulfides ((methylthio)benzene) in water. This supramolecularly controlled photooxidation based on the selective molecular binding of crown ether with photosensitizers may provide a feasible and applicable strategy for monitoring and modulating many photocatalysis processes in aqueous phase.

A New Pt(II) Complex with Anionic s-Triazine Based NNO-Donor Ligand: Synthesis, X-ray Structure, Hirshfeld Analysis and DFT Studies

The reaction of PtCl₂ with s-triazine-type ligand (HTriaz) (1:1) in acetone under heating afforded a new [Pt(Triaz)Cl] complex. Single-crystal X-ray diffraction analysis showed that the ligand (HTriaz) is an NNO tridentate chelate via two N-atoms from the s-triazine and hydrazone moieties and one oxygen from the deprotonated phenolic OH. The coordination environment of the Pt(II) is completed by one Cl⁻¹ ion trans to the Pt-N_(hydrazone). Hirshfeld surface analysis showed that the most dominant interactions are the H···H, H···C and O···H intermolecular contacts. These interactions contributed by 60.9, 11.2 and 8.3% from the whole fingerprint area, respectively. Other minor contributions from the Cl···H, C···N, N···H and C···C contacts were also detected. Among these interactions, the most significant contacts are the O···H, H···C and H···H interactions. The amounts of the electron transfer from the ligand groups to Pt(II) metal center were predicted using NBO calculations. Additionally, the electronic spectra were assigned based on the TD-DFT calculations.

A study of the effects of the polarity of the solvents acetone and cyclohexane on the luminescent properties of tryptophan

The luminescent properties of tryptophan in solvents less polar than water, such as acetone, and non-polar ones, such as cyclohexane, are experimentally studied and compared with theoretical calculations using time-dependent density functional theory (TD-DFT) methods. Since tryptophan may present different configurations and charge distributions, the most stable conformer is analyzed for both solvents, including its neutral and zwitterionic forms. To perform the simulation two clusters are proposed with the Zpt conformer in acetone: [Formula: see text] and [Formula: see text] , and four clusters with the Nag⁺ conformer in cyclohexane: (Trp)₁-(C₆H₁₂), (Trp)₂-(C₆H₁₂), (Trp)₃-(C₆H₁₂) and (Trp)₄-(C₆H₁₂), in order to conveniently emulate the concentration in each solvent by reducing the distance between adjacent tryptophan molecules as the concentration increases, since there is no control over the volume parameter. In each case, the UV-vis absorption is computed and compared with the experimental excitation spectra; the results show a good agreement. This calculation allows a more detailed analysis of the experimental results based on the properties of the molecular orbitals involved in electronic transitions. In the present work, a strong effect of the solvent acetone on tryptophan is observed; for this solvent, a charge transfer from the solute to solvent happens. This behavior does not occur with water (polar solvent) or cyclohexane (non-polar solvent). Finally, experimental spectroscopic data of Trp in cyclohexane are explained through the hydrogen bonds between amino acid molecules present in the fluorescent states. In this case, the theoretical and experimental results are compared and also show good agreement.

Excitation of rhodamine 800 in aqueous media: a theoretical investigation

The main goal of this work was to obtain a calculated absorption spectrum of rhodamine 800 in an aqueous solution, which most accurately reproduces the experimental one. To achieve this result, I used the hybrid functionals supported by Gaussian 16 software package. In this case, the basis set (6-31++G(d,p)) and the solvent model (IEFPCM) were not varied. The B3PW91 functional gave the best agreement with the experimental absorption spectrum of the dye in an aqueous medium. B3P86, B971, B972, B98, X3LYP, APF, HSE06, and N12SX functionals also give good absorption energy coincidence. The B3PW91/6-31++G(d,p)/IEFPCM theory level chosen in this way made it possible to calculate the various characteristics of rhodamine 800 in the ground and excited states. An important result of this work was the establishment of the vibronic nature of the short-wavelength smaller maximum of the absorption spectrum. The influence of the strong H-bond of the exocyclic nitrogen atom with the water molecule on the dye excitation was analyzed.

Formation of sandwich and multidecker complexes between O2 and alkali/alkaline earth metals: A DFT study

Abstract: Feasibility of formation of sandwich and multidecker complexes between O2 molecules and alkali/alkaline earth metal has been analyzed in the light of density functional theory (DFT). High value of...

Successive protonation of Lindqvist Hexaniobate, [Nb6O19]8-: electronic properties and structural distortions

Lindqvist Hexaniobate, [Nb6O19]8-, is an intriguing type of polyoxoniobate presenting a significant negative charge, high symmetry, robust structure and applications in photocatalysis. In this work, the [Nb6O19]8- polyanion was submitted...

Chemical transformation of Doubly N-Confused Porphodimethene to variants of (anti)Aromatic Doubly N-Confused Porphyrinoids and σ aromatic Doubly N-Confused Isophlorinoid

Chemical conversion of non-aromatic trans-doubly N-confused porphodimethene to hitherto unknown variants of doubly N-confused porphyrinoids/isophlorinoid have been unravelled by precise interplay between the types of oxidants, the types of meso-aryl...

Coumarin 102 excitation in aqueous media: contributions of vibronic coupling and hydration

For the first time, vibronic coupling was considered when analyzing the excitation of coumarin C102.

Antioxidant analysis of ultra-fast selectively recovered 4-hydroxy benzoic acid from fruits and vegetable peel waste using graphene oxide based molecularly imprinted composite

Food processing industries generate 25-30% of fruit and vegetable peel (F&VP) waste of the total produce, which are rich in polyphenolic antioxidants (PA). Sustainable solution for the above waste can be its valorization for the recovery of PA, often used as natural preservative. Present work reports rationally designed graphene oxide-based molecularly imprinted composites (GOMIPs) using ionic liquid 1-allyl-3-octylimidazolium chloride (A) as a green functional monomer for selective recovery of PA 4-Hydroxy benzoic acid (4HA) from F&VP/pomegranate peel (PGP) waste. GOMIP-A and GOMIP-V were characterized using various techniques for its successful synthesis. GOMIP-A attained equilibrium within 10 min with adsorption capacity of 190.56 μmol g-1 for 4HA. Developed HPLC method depicted selective recovery of 77.23% and 62.83% 4HA from F&VP and PGP waste respectively by GOMIP-A. Subsequently, desorbed 4HA from GOMIP-A matrices exhibited the antioxidant potential of 33.53% (F&VP extract) and 47.97% (PGP extract) for DPPH radical.

New perspectives on the laser initiation for metal tetrazine complexes: a theoretical study

In order to understand the relationship between laser initiation and charge transfer of metal tetrazine complexes (MTCs), several sets of MTCs with different metals and ligands were designed and their charge transfer (CT) characters were examined using a time-dependent density functional theory method (TD-DFT) in combination with UV-vis spectra, hole-electron distribution, interfragment charge transition, and transition density matrix analyses. Results show that Fe(II), Mn(II), and Cu(II) are suitable divalent transition metal cores in constructing the optical initiation tetrazine complexes. By replacing the divalent metal cores with a monovalent center, new sets of complexes are proved to possess metal-to-ligand charge transfer (MLCT) character and stronger absorption intensity in the near-infrared (NIR) region, which implies that monovalent MTCs are more in favor of low-energy laser initiation than divalent MTCs. Reasonable tuning of the structure of pyrazole substituent can expect to enhance the explosive performance while preserving the optical characteristics, which is an important design principle. This work thoroughly depicts the photoactive states for MTCs and gives a train of thought to explore new desirable laser initiation explosives.