Ring Atoms Research Articles

Enoxacin fluoroquinolone antibacterial agent complexes with Pt(IV), Ru(III) and Ir(III) ions: Synthesis, spectroscopic, physicochemical characterizations and biological studies

The synthesis, physicochemical characterizations, and biological investigations on the chelation of the antibiotic medication enoxacin (EXN) with certain vital metal ions, such as platinum(IV), ruthenium(III), and iridium(III) are discussed in this study. These compounds structures were interpreted based on elemental analysis and spectral measurements (FTIR, 1H-NMR, UV-Vis electronic, and XRD). The findings show that there is same coordination pathway for the chelation behavior of enoxacin complexes: a monodentate manner. The Pt(IV), Ru(III), and Ir(III) complexes are coordinated through the N atom of the piperazine ring, which is an unusual mode of coordination for this class of compounds. The dissolved complexes in DMSO were found to have non-electrolyte nature based on their molar conductance measurements. The formula for these complexes is [Pt(EXN)3(H2O)2Cl] (1), [Ru(EXN)3(H2O)3] (2), and [Ir(EXN)3(H2O)3] (3). Using scanning electron microscope (SEM) analysis and X-ray powder diffraction (XRD), the nano-scale range of the Pt(IV), Ru(III), and Ir(III) complexes has been determined. Results of in vitro cytotoxicity were examined using MCF-7 cells (human breast cancer cell line) and HepG-2 cells (human hepatocellular carcinoma) that had been grown. The cytotoxic activity of the metal complexes demonstrated a cytotoxic effect against the growth of human breast and liver cancer cell lines.
 KEY WORDS: Enoxacin, Platinum(IV), Complexity, Spectral analyses, Biological assessments
 Bull. Chem. Soc. Ethiop. 2024, 38(3), 685-699. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i3.11

Correction for the calculated XANES spectra of 1,4,7,10-alkyltetracenes considering the total electron yield (TEY) efficiency of sp2- and sp3-carbon atoms.

The calculated X-ray-absorption-near-edge-structure (XANES) spectra in the CK region of 1,4,7,10-alkyltetracenes, which are composed of both sp2-C atoms in the tetracene ring and sp3-C atoms in the alkyl-chains, can be corrected by considering the total electron yield (TEY) efficiency of sp3-C relative to sp2-C. In the correction, the previously measured TEY efficiency of k = 0.51 is applied to the calculated transition probabilities for sp3-C atoms. Then the calculated CK-XANES obtained from density functional theory (DFT) calculations can well reproduce the measured TEY-CK-XANES. Especially, the calculated π*/σ* peak intensity ratios are in good agreement with the measured ones. This suggests that a similar correction for the calculated XANES is necessary for compounds composed of multi-components with different TEY efficiencies.

Review of: "C70 Fullerenes Closed hollow cages are made of interconnected carbon atoms in pentagonal and hexagonal rings with a cage-like melted ring structure that resembles a rugby ball"

Review of: "C70 Fullerenes Closed hollow cages are made of interconnected carbon atoms in pentagonal and hexagonal rings with a cage-like melted ring structure that resembles a rugby ball"

Review of: "C70 Fullerenes Closed hollow cages are made of interconnected carbon atoms in pentagonal and hexagonal rings with a cage-like melted ring structure that resembles a rugby ball"

Review of: "C70 Fullerenes Closed hollow cages are made of interconnected carbon atoms in pentagonal and hexagonal rings with a cage-like melted ring structure that resembles a rugby ball"

Photocatalytic degradation of enrofloxacin with CoAl-LDH mediated persulfate system: Efficiency evaluations and reaction pathways

Residual enrofloxacin (ENR) exposed in aqueous environments is challenging to the ecosphere. In this work, a layered double hydroxide CoAl-LDH was used to activate the common oxidizing agent persulfate (PS) for photodegradation of ENR, and the degradation pathways of ENR were scrutinized and elucidated. The results indicated that, under the optimal conditions obtained through orthogonal experiments, even though the degradation rate of ENR was as high as 97.72%, the removal of total organic carbon (TOC) from the system was only about 30%. Eleven probable reaction pathways were categorized, and thirty-one types of intermediates were identified in participating in the complex degradation process. The major products of ENR were P4 (C17H20FN3O3), P22 (C19H22FN3O4), P19 (C17H18FN3O3), which are mainly derived from the cleavage of the piperazine groups and quinolone rings. Density functional theory (DFT) calculations of the Fukui index for ENR revealed that the two N atoms in the piperazine ring were the core reactive sites in triggering the degradation chains, which were sensitive for electrophilic attack by the dominant radicals (•OH and SO4•-) generated from the composite PS-UV-CoAl-LDH system.

Crystal structure and synchrotron X-ray powder reference pattern for the porous pillared cyanonickelate, Ni(3-amino-4,4′-bipyridine)[Ni(CN)4

The structure of Ni(3-amino-4,4′-bipyridine)[Ni(CN)4] (or known as Ni-BpyNH2) in powder form was determined using synchrotron X-ray diffraction and refined using the Rietveld refinement technique (R = 8.8%). The orthorhombic (Cmca) cell parameters were determined to be a = 14.7218(3) Å, b = 22.6615(3) Å, c = 12.3833(3) Å, V = 4131.29(9) Å3, and Z = 8. Ni-BpyNH2 forms a 3-D network, with a 2-D Ni(CN)4 net connecting to each other via the BpyNH2 ligands. There are two independent Ni sites on the net. The 2-D nets are connected to each other via the bonding of the pyridine “N” atom to Ni2. The Ni2 site is of six-fold coordination to N with relatively long Ni2–N distances (average of 2.118 Å) as compared to the four-fold coordinated Ni1–C distances (average of 1.850 Å). The Ni(CN)4 net is arranged in a wave-like fashion. The functional group, –NH2, is disordered and was found to be in the m-position relative to the N atom of the pyridine ring. Instead of having a unique position, N has ¼ site occupancy in each of the four m-positions. The powder reference diffraction pattern for Ni-BpyNH2 was prepared and submitted to the Powder Diffraction File (PDF) at the International Centre of Diffraction Data (ICDD).

Charging modulation of the pyridine nitrogen of covalent organic frameworks for promoting oxygen reduction reaction

Covalent organic frameworks (COFs) are ideal templates for constructing metal-free catalysts for the oxygen reduction reaction due to their highly tuneable skeletons and controllable porous channels. However, the development of highly active sites within COFs remains challenging due to their limited electron-transfer capabilities and weak binding affinities for reaction intermediates. Herein, we constructed highly active catalytic centres by modulating the electronic states of the pyridine nitrogen atoms incorporated into the frameworks of COFs. By incorporating different pyridine units (such as pyridine, ionic pyridine, and ionic imidazole units), we tuned various properties including dipole moments, reductive ability, hydrophilicity, and binding affinities towards reaction intermediates. Notably, the ionic imidazole COF (im-PY-BPY-COF) exhibited greater activity than the neutral COF (PY-BPY-COF) and ionic pyridine COF (ion-PY-BPY-COF). Specifically, im-PY-BPY-COF demonstrated a half-wave potential of 0.80 V in 0.1 M KOH, outperforming other metal-free COFs. Theoretical calculations and in situ synchrotron radiation Fourier transform infrared spectroscopy confirmed that the carbon atoms in the ionic imidazole rings improved the activity by facilitating binding of the intermediate OOH* and promoting the desorption of OH*. This study provides new insights into the design of highly active metal-like COF catalysts.

Molecular dynamics investigation of ionanofluids (INFs): Towards a deeper understanding of their thermophysical, structural and dynamical properties

Ionanofluids (INFs) are a novel type of heat transfer fluids consisting of fine nanoparticles suspended in ionic liquids (ILs). They exhibit improved thermal properties, including enhanced thermal conductivity, non-volatility, and non-flammability, making them ideal candidates for various applications, especially solar concentrators. In this work, for the first time, molecular dynamics (MD) simulations are used to investigate the thermophysical, structural, and dynamical properties of a specific INF composed of the [HMIM][BF4] IL and SiC nanoparticles in the temperature range of 298.15–338.15 K and at different nanoparticle volume fractions, i.e. 1.10 %, 2.27 %, and 3.47 %. Radial distribution functions (RDFs) revealed a strong structural correlation between the fluorine atoms of anion and the HR atom of the cation ring and also with the carbon and silicon atoms of the nanoparticle. The results showed that with increasing the volume fraction of nanoparticles, ions tend to have more interactions with nanoparticles, and the interactions between the anions and cations decrease. As a result, the thermal conductivity, viscosity, and density of ions in the INF increases. Finally, we made some comparisons between the simulated thermal conductivities and viscosities of the studied INF with classical models. The results showed that, in some cases, the simulation results were even better than some models compared to the experimental values. The insights obtained from this study not only enhance our understanding of the structure and dynamic behavior of the INF, but also can contribute to the development of innovative materials and more efficient solar thermal systems.

Structure-based design and synthesis of BML284 derivatives: A novel class of colchicine-site noncovalent tubulin degradation agents

Our previous studies have demonstrated that BML284 is a colchicine-site tubulin degradation agent. To improve its antiproliferative properties, 45 derivatives or analogs of BML284 were designed and synthesized based on the cocrystal structure of BML284 and tubulin. Among them, 5i was the most potent derivative, with IC50 values ranging from 0.02 to 0.05 μM against the five tested tumor cell lines. Structure–activity relationship studies verified that the N1 atom of the pyrimidine ring was the key functional group for its tubulin degradation ability. The 5i–tubulin cocrystal complex revealed that the binding pattern of 5i to tubulin is similar to that of BML284. However, replacing the benzodioxole ring with an indole ring strengthened the hydrogen bond formed by the 2-amino group with E198, which improved the antiproliferative activity of 5i. Compound 5i effectively suppressed tumor growth at an intravenous dose of 40 mg/kg (every 2 days) in paclitaxel sensitive A2780S and paclitaxel resistant A2780T ovarian xenograft models, with tumor growth inhibition values of 79.4% and 82.0%, respectively, without apparent side effects, showing its potential to overcome multidrug resistance. This study provided a successful example of crystal structure–guided discovery of 5i as a colchicine-targeted tubulin degradation agent, expanding the scope of targeted protein degradation.

Mid-IR and CH stretching vibrational circular dichroism spectroscopy to distinguish various sources of chirality: The case of quinophaneoxazoline based ruthenium(II) complexes.

Five diastereomers of ruthenium(II) complexes based on quinolinophaneoxazoline ligands were investigated by vibrational circular dichroism (VCD) in the mid-IR and CH stretching regions. Diastereomers differ in three sources of chirality: the planar chirality of the quinolinophane moiety, the central chirality of an asymmetric carbon atom of the oxazoline ring, and the chirality of the ruthenium atom. VCD, allied to DFT calculations, has been found to be effective in disentangling the various forms of chirality. In particular, a VCD band is identified in the CH stretching region directly connected to the chirality of the metal. The analysis of the calculated VCD spectra is carried out by partitioning the complexes into fragments. The anharmonic analysis is also performed with a recently proposed reduced-dimensionality approach: such treatment is particularly important when examining spectroscopic regions highly perturbed by resonances, like the CH stretching region.

Structure elucidation {single X-ray crystal diffraction studies, Hirshfeld surface analysis, DFT} and antibacterial studies of 1,2-benzothiazine metal complexes

The 2-benzyl-4‑hydroxy-1,1-dioxo-1,2-benzothiazine-3-carboxylic acid methyl ester i.e., ligand 1 was utilized to synthesize Mn(II) 2, Co(II) 3, Ni(II) 4, Cu(II) 5 and Zn(II) 6 derived metal complexes in mild basic conditions. The structural investigation was carried out by UV–vis, FT-IR, NMR spectroscopy, CHN analysis, conductivity measurement, ESI-MS analysis and magnetic susceptibility techniques. The X-ray diffraction analysis confirmed the octahedral and distorted square pyramidal geometries of the cobalt and copper complexes. The ligand 1 coordinated with metal centres through enolic oxygen atoms of the thiazine ring and ester group while methanol coordinated with metal center via oxygen atom. The Hirshfeld surface analysis (HSA) was utilized to determine the intermolecular interactions. In support of the experimental data, DFT studies were also performed for the cobalt and copper complexes. The NBO analysis resulted in the large stabilization values 11.91 and 12.35 kcal/mol for the cobalt and copper complexes. The global reactivity indicated the higher values of hardness and the large values of FMO analysis which support the higher stability of the metal complexes. The synthesized compounds were also evaluated against six bacterial strains to check their antibacterial potential. It was observed from results that highest activity was depicted by copper complex 5 against B. subtilis and the zone of inhibition is 23.4 ± 0.6 mm which is comparable to ampicillin (standard drug).

Syntheses, characterizations, crystal structures and Hirshfeld surface analyses of methyl 4-[4-(di-fluorometh-oxy)phen-yl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate, isopropyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate and tert-butyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate.

The crystal structures and Hirshfeld surface analyses of three similar compounds are reported. Methyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate, (C21H23F2NO4), (I), crystallizes in the monoclinic space group C2/c with Z = 8, while isopropyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carb-oxyl-ate, (C23H27F2NO4), (II) and tert-butyl 4-[4-(di-fluoro-meth-oxy)phen-yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa-hydro-quinoline-3-carboxyl-ate, (C24H29F2NO4), (III) crystallize in the ortho-rhom-bic space group Pbca with Z = 8. In the crystal structure of (I), mol-ecules are linked by N-H⋯O and C-H⋯O inter-actions, forming a tri-periodic network, while mol-ecules of (II) and (III) are linked by N-H⋯O, C-H⋯F and C-H⋯π inter-actions, forming layers parallel to (002). The cohesion of the mol-ecular packing is ensured by van der Waals forces between these layers. In (I), the atoms of the 4-di-fluoro-meth-oxy-phenyl group are disordered over two sets of sites in a 0.647 (3): 0.353 (3) ratio. In (III), the atoms of the dimethyl group attached to the cyclo-hexane ring, and the two carbon atoms of the cyclo-hexane ring are disordered over two sets of sites in a 0.646 (3):0.354 (3) ratio.

The σ+π dual aromaticity of typical bi-tetrazole ring molecule TKX-50.

Two complexes of dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) were employed to evaluate the aromaticity of their tetrazole rings via deep analysis such as the electronic structure, the ZZ component of the natural chemical shielding tensor (NICSZZ) and component orbitals, localized orbital locator purely contributed by σ-orbitals (LOL-σ) and localized orbital locator purely contributed by π-orbitals (LOL-π), the anisotropy of the induced current density (AICD) and the ZZ component of iso-chemical shielding surface (ICSSZZ) of these tetrazole rings thereof. The conclusion shows: that all tetrazole rings and bi-tetrazole rings in complexes have strong σ and a comparable strength π double aromaticity; all these magnetic shields almost symmetrically increase from the central axis to the tetrazole ring atoms; tetrazole rings in complex II show a little stronger dual aromaticity than that in complex I mainly due to the different orientation of the fragment 2 encompassing two hydroxylamine groups resulting in different effects on the contributions of σ orbitals and π orbitals to total aromaticity of tetrazole rings thereof; the difference in aromaticity is fundamentally caused by the atoms O with stronger electron-withdrawing than atom N in fragment 2 interact with bi-tetrazole ring through O in complex I but through N in complex II.

O-doped g-C3N4 prepared in pyridine for efficiently photocatalytic hydrogen production

ABSTRACT Oxygen-doped g-C3N4 with pyridine ring (POCN) was synthesized by easily thermal polymerization of urea, pyridine solution, and ammonium acetate to improve photocatalytic hydrogen production. The experimental results indicate that pyridine was incorporated into the tri-s-triazine structure of g-C3N4. The O atoms were modified to g-C3N4 by replacing the N atoms (C–N=C) of the triazine ring. The photocatalytic activity for the hydrogen production rate of optimized POCN was 1018 µmol g–1 h–1, approximately 30 times higher than that of bulk g-C3N4 (CN) under visible light irradiation (λ > 420 nm). The high stability of POCN was confirmed through cycling tests for 30-h, XRD patterns, and SEM images. The pyridine incorporation can significantly enhance surface charge transfer efficiency. The oxygen modification can greatly promote visible light absorption (600 nm) and photogenerated electron–hole pairs separation. This work provides a suitable strategy to synthesize g-C3N4 based on metal-free photocatalysts for highly efficient photocatalytic hydrogen generation performance.

Insights into the crystal structure investigation and virtual screening approach of quinoxaline derivatives as potent against c-Jun N-terminal kinases 1

Quinoxaline derivatives are an important class of heterocyclic compounds in which N replaces one or more carbon atoms of the naphthalene ring and exhibit a wide spectrum of biological activities and therapeutic applications. As a result, we were encouraged to explore a new synthetic approach to quinoxaline derivatives. In this work, we synthesized two new derivatives namely, ethyl 4-(2-ethoxy-2-oxoethyl)-3-oxo-3,4-dihydroquinoxaline-2-carboxylate (2) and 3-oxo-3,4-dihydroquinoxaline-2-carbohydrazide (3) respectively. Their structures were confirmed by single-crystal X-ray analysis. Hirshfeld surface (HS) analysis is performed to understand the nature and magnitude of intermolecular interactions in the crystal packing. Density functional theory using the wb97xd/def2-TZVP method was chosen to explore their reactivity, electronic stability and optical properties. Charge transfer (CT) and orbital energies were analyzed via natural population analysis (NPA), and frontier molecular orbital (FMO) theory. The calculated excellent static hyperpolarizability (βo) indicates nonlinear optical (NLO) properties for 2 and 3. Both compounds show potent activity against c-Jun N-terminal kinases 1 (JNK 1) based on structural activity relationship studies, further subjected to molecular docking, molecular dynamics and ADMET analysis to understand their potential as drug candidates. Communicated by Ramaswamy H. Sarma

Atomic-level mechanisms of short-circuit diffusion in materials

Abstract This paper reviews the recent progress in understanding the atomic mechanisms of short-circuit diffusion along materials interfaces, such as grain and interphase boundaries, as well as lattice and interfacial dislocations/disconnections. Recent atomistic computer simulations have shown that short-circuit diffusion is dominated by collective atomic rearrangements in the form of strings and rings of mobile atoms. The process is dynamically heterogeneous in space and time and has many features in common with atomic dynamics in supercooled glass-forming liquids. We discuss examples of grain boundary, interphase boundary, and dislocation diffusion in metals and alloys, including the solute effect on the diffusion rates and mechanisms. Interphase boundaries are exemplified by Al–Si interfaces with diverse orientation relationships and atomic structures. The hierarchy of short-circuit diffusion paths in materials is reviewed by comparing the rates of grain boundary, interphase boundary, and dislocation diffusion. Future directions in the field of short-circuit diffusion in defect core regions are discussed.

Synthesis, characterization and theoretical aspects of copper and zinc divalent ion complexes with azo dye derived from 4,5-diphenylimidazole

Azo dye ligand derived from 4,5-diphenyl imidazole and 4,4-diaminodiphenylmethane was synthesized by diazomium coupling reaction. In this reaction an amine (4,4-diaminodiphenylmethane was converted to the diazonium salt and coupled with 4,5-diphenyl imidazole. The bright coloured Cu(II) and Zn(II) complexes with this ligand were synthesized by refluxing the latest with both metals chloride salts. The prepared compounds were characterized by 1H-NMR, 13C-NMR, FTIR, UV-Visible, molar conductivity and atomic absorption. By the infrared data, the coordination between copper and zinc ions and the azo ligand achieved through the nitrogen of the azo group and one of the nitrogen atoms in the imidazole ring. By the molar conductivity test, the non- electrolytic nature of both complexes was also confirmed. The suggested structure for these complexes is octahedral. Using density functional theory (DFT) some theoretical data was obtained for the synthesized complexes. The obtained data include the highest occupied and the lowest unoccupied molecular orbitals energy (HOMO and LUMO), electron density, thermodynamic functions (ΔG°, ΔS°, ΔH°, ΔE°), ionization potential (IP), electron affinity (EA), electrophilicity(ὠ), electronegativity (En), chemical hardness (η) and dipole moment (μ). According to these studied parameters some properties of the two complexes were explained and discussed.
 KEY WORDS: Cu(II) and Zn(II) complexes, Azo ligand, 4,5-Diphenylimidazole, 4,4-Diaminodiphenylmethane, Theoretical study
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 313-323. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.4

4-Thiaproline accelerates the slow folding phase of proteins containing cis prolines in the native state by two orders of magnitude.

The cis/trans isomerization of peptidyl-prolyl peptide bonds is often the bottleneck of the refolding reaction for proteins containing cis proline residues in the native state. Proline (Pro) analogues, especially C4-substituted fluoroprolines, have been widely used in protein engineering to enhance the thermodynamic stability of peptides and proteins and to investigate folding kinetics. 4-thiaproline (Thp) has been shown to bias the ring pucker of Pro, to increase the cis population percentage of model peptides in comparison to Pro, and to diminish the activation energy barrier for the cis/trans isomerization reaction. Despite its intriguing properties, Thp has been seldom incorporated into proteins. Moreover, the impact of Thp on the folding kinetics of globular proteins has never been reported. In this study, we show that upon incorporation of Thp at cisPro76 into the thioredoxin variant Trx1P the half-life of the refolding reaction decreased from ~2 h to ~35 s. A dramatic acceleration of the refolding rate could be observed also for the protein pseudo wild-type barstar upon replacement of cisPro48 with Thp. Quantum chemical calculations suggested that the replacement of the Cγ H2 group by a sulfur atom in the pyrrolidine ring, might lower the barrier for cis/trans rotation due to a weakened peptide bond. The protein variants retained their thermodynamic stability upon incorporation of Thp, while the catalytic and enzymatic activities of the modified Trx1P remained unchanged. Our results show that the Pro isostere Thp might accelerate the rate of the slow refolding reaction for proteins containing cis proline residues in the native state, independent from the local structural environment.

Understanding into atomic structures and electronic properties from the analysis of intramolecular junctions in carbon nanotubes

Octuplet arrangements of intra-molecular junctions (IJs) are selected and studied in order to forecast each one's atomic structure, quantum density of states of CNTs with imperfections, and electronic transmittals. Each of these can be divided into groups of triplets, specifically those that exhibit comparable characteristics to one another, such as Semiconductor_Semiconductor IJs (SC_SC IJs) (in arrangements of first, second, fifth and eight), Metal_Metal IJs (in arrangements of third and seventh) and Semiconductor_Metal IJs (in arrangements of fourth and sixth). The quantum density of states of SC_SC IJs results in semiconductors with the same order as before, but with a reduced band gap as compared to the primary standards. Additionally, a resized image of quantum density of states is provided to demonstrate the specifics of the divergence near the Fermi limit. quantum density of states for CNTs-IJs (fifth, fourth) – (fifth, fourth) (SC_SC) estimated across a handful of rings at the intersection indicated by the blue lines is shown through the illustration. The hexagonal-assembly of CNTs contains pentagons & heptagon-paired imperfections, which can alter CNTs’ helicity and their basic electronic framework. The red lines indicate the quantum density of states of Perfect-CNTs with indices (fifth, fourth). Despite being semiconductors by nature, Perfect-CNTs (fifth, fourth) exhibit a band gap around 1.22 eV. The semiconductor Perfect-CNTs with indices (seventh, fourth) have a quantum density of states that is mirrored around the Fermi limit (E = 0). Additionally, at the Fermi limit, it has a value that does not equal zero, along with a difference in particle energy. The picture shows that the behavior of CNTs-IJs quantum density of states changes from being purely semiconductor-like to becoming less like a semiconductor when mixed with metallic CNTs at the intersection. The combination of metal and semiconductor is tangible. It changes from one system to another, beginning as a semiconductor and changing into a semiconductor with a considerable number of switching operations. The observation shows that the semiconductor with the indices (seventh, third) and the metal carbon nanotubes with the indices (seventh, fourth) both have zero QDS at the Fermi energy level. Despite being diluted within a few atomic rings, the quantum density of states in the case of CNTs-IJs (seventh, third) – (seventh, fourth) remains at 0.0 at the Fermi energy level due to being diluted within a few atomic rings.

Covalent triazine reducing the defects by coordination roles and inhibiting I− migration by anion-π interaction for efficient perovskite solar cell

The grain boundary defects related non-radiative recombination, I− migration, and lead leakage problems are the foundational and fundamental aspects for the perovskite solar cells. Herein, covalent triazine frameworks (CTFs) are introduced into the perovskite film to address these problems. CTFs can passivate the uncoordinated Pb2+ defects at grain boundary and reduce the lead leakage based on the coordination interaction between nitrogen atoms in triazine ring and Pb2+. CTFs can also inhibit the I− migration and reduce the I− vacancy defects based on the anion-π interaction between electron-deficient triazine ring and I−. Benefited from the passivated grain boundary defects and inhibited I− migration by CTFs, the modified target device achieves a power conversion efficiency of 23.05 % with improved humidity stability and thermal stability. Therefore, this work lays the foundation for obtaining effective, stable, and environmentally friendly perovskite solar cells.