Octahedral Geometry Research Articles

The Impact of Coordination Distortion on Magnetic Properties of Co (II) Single‐Ion Magnets With Trigonal Prism Coordination Geometry

ABSTRACTTwo Co (II) compounds [Co (abs)2]·2H2O (1) and [Co (pabs)2] (2) (Habs = N‐(pyridine‐2′‐yl methylene)‐2‐aminobenzene sulfonic acid, Hpabs = N‐[(pyridine‐2′‐yl)(phenyl)methylene]‐2‐aminobenzene sulfonic acid) were synthesized by the introduction of sulfonate ligands with different substitutions. Both Co (II) ions are located in a trigonal prism coordination environment with different coordination distortions. Static magnetic studies and theoretical calculations found that easy‐axis magnetic anisotropy is present in both complexes. The contributions of the negative D values are principally derived from the first quartet excited state. Dynamic magnetic investigations uncovered that both compounds have field‐induced single‐ion magnet (SIM) behavior and their magnetic relaxations mainly realize through Raman and direct pathways.

Heterostructural interface engineering for ultrawide-gap nitrides from first principles: TaC / AlN and TaC / GaN rocksalt-wurtzite interfaces

Epitaxial lattice matching is an important condition for the formation of coherent interfaces with low defect densities. However, lattice-matched substrates with the same crystal structure as the active layer are often not available, suggesting opportunities for utilizing heterostructural interfaces. For example, at high Al contents that are interesting for ultrawide-gap applications in power electronics, AlxGa1−xN semiconductor alloys in the (0001) orientation of the wurtzite (wz) structure become lattice-matched to (111)-oriented rocksalt (rs) TaC substrates. To predict the expected interface atomic structures under different synthesis conditions, we perform high-throughput density-functional-theory calculations, using an algorithm for systematic sampling of the possible stacking sequences of the atomic layers on the in-plane hexagonal lattice. The approach considers octahedral, tetrahedral, and prismatic coordination motifs, and is generally applicable for the modeling of commensurate rs/wz heterostructural interfaces. Our results provide guidance for synthesis control of substrate-film bonding and the polarity of ultrawide-gap AlxGa1−xN alloys on TaC substrates. Published by the American Physical Society 2024

Affecting Charges and Structures of {Bi6} Architectures by 12‐Electron Transition Metal Fragments

AbstractMolecules based on polyatomic bismuth substructures are currently attracting a lot of attention owing to this heavy and essentially non‐toxic element's uncommon chemical and physical properties, which include unprecedented bonding properties. Hexaatomic {Bi6} substructures that underly more complex cluster structures were recently reported to adopt different structures or exhibit different structural details as a consequence of the charge of the {Bi6} unit. This leads to either crown‐shaped cycles for a nominal Bi66− or differently distorted trigonal prisms for compositions close to Bi62−. It was predicted by quantum chemistry that Bi64− should adopt a distinctly distorted boat‐like shape, yet a corresponding compound has remained elusive. Here, we report a proof of this assumption by the synthesis of [K(crypt‐222)]2[Bi6{Zn(hmds)}2] ⋅ 1.5THF (1), comprising a bimetallic [Bi6{Zn(hmds)}2]2− cluster that fulfills the prediction for the geometric and electronic structure of the missing link (crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo‐[8.8.8]hexa‐cosane, hmds=hexamethyldisilazanid). A detailed quantum chemical study shows how the nature of Lewis‐acidic transition metal complexes—in particular, 12‐electron fragments—control and fine‐tune the resulting {Bi6} architectures in accordance with the degree of electron‐withdrawal from the polybismuthide core.

Growth Phenomena and Bandgap Shift in Melt‐Grown β‐(InxGa1−x)2O3 Alloys

β‐Ga2O3 is an emerging ultra‐wide bandgap semiconductor with great promise for power electronics and optoelectronics. Alloys in the In2O3‐Ga2O3 system are interesting for optoelectronic applications, particularly where bandgap tuning is desirable. Herein, β‐(InxGa1–x)2O3 alloys with target compositions x = 0.025 or 0.10 are grown from the melt using the Czochralski and vertical gradient freeze techniques. Growth with 10 mol% In yields only small, needle‐like crystals, while 2.5 mol% In allows growth of centimeter‐sized single crystals. A substantial degree of indium segregation is unveiled by spatial measurements of lattice parameters and the bandgap. The bandgap decreases by a maximum of 0.28 eV in the case of the highest In content crystals. Z‐contrast transmission electron microscopy confirms a solely octahedral coordination of In in the β‐Ga2O3 lattice. With indium concentrations higher than 2.5 mol%, samples contain micron‐scale voids that impart a dark coloration. All measured crystals are electrically conductive, with carrier concentrations varying 1016–1017 cm−3 depending upon the location of the sample in the growth. Lastly, a unique luminescence with unknown origin centered around 2.0 eV is revealed by photoluminescence spectroscopy.

Combination of Ambient and High‐Temperature Beryllium Nitride Motifs in W2Be4N5 and W4Be8N9

Compounds of transition metals and beryllium have a wide range of applications, from everyday tools to high tech applications. Remarkably, no single ternary beryllium nitride with a transition metal is known. Here, we report on the synthesis and properties of the first transition metal nitridoberyllates, namely W2Be4N5 and W4Be8N9. Both compounds were synthesized in a high‐temperature high‐pressure approach from Be3N2 and W, using azide generated N2 as an oxidizing agent. The crystal structures, consisting of alternating layers of WN6 trigonal prisms and BeN4 tetrahedra, were elucidated by single‐crystal X‐ray diffraction (sc‐XRD). The separating nitridoberyllate layers show either ambient temperature (α‐Be3N2 type) or high temperature (β‐Be3N2 type) motifs. W2Be4N5 was further corroborated by infrared (IR), nuclear magnetic resonance (NMR) and UV‐VIS spectroscopy and vibrating sample magnetometry (VSM) measurements. The latter revealed a mixed valence with an intermediate oxidation state of 3.5 for the W atoms. Both, the synthesis of the first transition metal nitridoberyllates and the synthesis approach using elemental W pave the way to a new field of nitride chemistry.

Combination of Ambient and High-Temperature Beryllium Nitride Motifs in W2Be4N5 and W4Be8N9.

Compounds of transition metals and beryllium have a wide range of applications, from everyday tools to high tech applications. Remarkably, no single ternary beryllium nitride with a transition metal is known. Here, we report on the synthesis and properties of the first transition metal nitridoberyllates, namely W2Be4N5 and W4Be8N9. Both compounds were synthesized in a high-temperature high-pressure approach from Be3N2 and W, using azide generated N2 as an oxidizing agent. The crystal structures, consisting of alternating layers of WN6 trigonal prisms and BeN4 tetrahedra, were elucidated by single-crystal X-ray diffraction (sc-XRD). The separating nitridoberyllate layers show either ambient temperature (α-Be3N2 type) or high temperature (β-Be3N2 type) motifs. W2Be4N5 was further corroborated by infrared (IR), nuclear magnetic resonance (NMR) and UV-VIS spectroscopy and vibrating sample magnetometry (VSM) measurements. The latter revealed a mixed valence with an intermediate oxidation state of 3.5 for the W atoms. Both, the synthesis of the first transition metal nitridoberyllates and the synthesis approach using elemental W pave the way to a new field of nitride chemistry.

Crystal structures of two polymorphs for fac-bromidotricarbonyl[4-(4-methoxyphenyl)-2-(pyridin-2-yl)thiazole-κ2 N,N′]rhenium(I)

Crystallization of the title compound, fac-[ReBr(ppt-OMe)(CO)3] (ppt-OMe = C15H12N2OS), from CH2Cl2/n-pentane (1:5 v/v) at room temperature gave two polymorphs, which crystallize in monoclinic (P21/c; α form) and orthorhombic (Pna21; β form) space groups. The ReI complex molecules in either polymorph adopt a six-coordinate octahedral geometry with three facially-oriented carbonyl ligands, one bromido ligand, and two nitrogen atoms from one chelating ligand ppt-OMe. In the crystal, both polymorph α and β form di-periodic sheet-like architectures supported by multiple hydrogen bonds. In polymorph α, two types of hydrogen bonds (C—H...O) are found while, in polymorph β, four types of hydrogen bonds (C—H...O and C—H...Br) exist.

Central metal coordination environment optimization enhances Na diffusion and structural stability in Prussian blue analogues

Prussian blue analogues, particularly metal hexacyanoferrates with double octahedral coordination (DOC) structures, hold great promise as cathode materials for sodium-ion batteries. However, their practical application is hindered by limited structural stability and restricted ionic diffusion channels inherent to the DOC structure. In this study, we have successfully integrated a mixed tetrahedral and octahedral coordination (TOC) structure with the DOC structure by a dual polymerization and high-entropy strategy, thereby optimizing the central metal coordination environment in hexacyanoferrate cathodes. It leverages the TOC structure's superiorities in structural stability and ionic diffusion, resulting in a hexacyanoferrate-based cathode that exhibits exceptional performance, with a capacity retention of 81.6% after 1000 cycles at 0.5 A g-1 and high rate capabilities of 96.7 and 89.1 mAh g-1 at 0.5 and 1 A g-1, respectively. These findings not only underscore the potential of the TOC design for prussian blue cathodes but also pave the way for the development of high-performance, durable sodium-ion battery systems.

Conformational Changes and Coordination Stability of Flexible Tripeptides During Ni(II)-mediated Self-assembly.

The rational design of artificial supramolecular structures with specific properties and functions hinges the comprehensive understanding of the coordination and noncovalent interactions driving self-assembly. Herein, the self-assembly of supramolecular systems through octahedral coordination between Ni(II) ions and a flexible tripeptide was theoretically investigated using quantum chemical calculations. These calculations utilized the B3LYP functional with the polarizable continuum model. Our results indicate that tridentate sites have a greater propensity for coordination, and that the presence of chloride anions and conformational shifts enhance bidentate and monodentate coordination. Insights into the effect of counter anions on the stability of octahedral coordination and the prerequisites for self-assembly were gained by determining the stable conformation and potential reaction pathways of the tripeptide before and after adding chloride anions through an efficient automated conformational search. The formation of intramolecular hydrogen bonding interactions during the conformational changes was also studied using model calculations. Possible processes for initial self-assembly of tripeptide were proposed. This study enhances the fundamental understanding of the conformational behavior of building blocks during supramolecular formation and advance the potential for constructing future bioinspired complexes.

Tuning the Properties of Rigidified Acyclic DEDPA2- Derivatives for Application in PET Using Copper-64.

We present a detailed investigation of the coordination chemistry toward [natCu/64Cu]copper of a series of H2DEDPA derivatives (H2DEDPA = 6,6'-((ethane-1,2-diylbis(azanediyl))bis(methylene))dipicolinic acid) containing cyclohexyl (H2CHXDEDPA), cyclopentyl (H2CpDEDPA) or cyclobutyl (H2CBuDEDPA) spacers. Furthermore, we also developed a strategy that allowed the synthesis of a H2CBuDEDPA analogue containing an additional NHBoc group at the cyclobutyl ring, which can be used for conjugation to targeting units. The X-ray structures of the Cu(II) complexes evidence distorted octahedral coordination around the metal ion in all cases. Cyclic voltammetry experiments (0.15 M NaCl) evidence quasi-reversible reduction waves associated with the reduction of Cu(II) to Cu(I). The complexes show a high thermodynamic stability, with log KCuL values of 25.11(1), 22.18(1) and 20.19(1) for the complexes of CHXDEDPA2-, CpDEDPA2- and CBuDEDPA2-, respectively (25 °C, 1 M NaCl). Dissociation kinetics experiments reveal that both the spontaneous- and proton-assisted pathways operate at physiological pH. Quantitative labeling with 64CuCl2 was observed at 0.1 nmol for CHXDEDPA2- and CpDEDPA2-, 0.025 nmol for CBuDEDPA2- and 1 nmol for CBuDEDPA-NHBoc2-, with no significant differences observed at 15, 30, and 60 min. The radio-complexes are stable in PBS over a period of 24 h.

Sonodynamic Cancer Therapy by Mn(I)-tricarbonyl complexes via Ultrasound-triggered CO release and ROS generation.

A novel ferrocene conjugated Mn(I)-tricarbonyl complex viz [Mn(Fc-tpy)(CO)3Br] (Mn2) where, Fc-tpy = 4'-ferrocenyl-2,2':6',2''-terpyridine was synthesized and fully characterized along with its non-ferrocene analog [Mn(Ph-tpy)(CO)3 Br] Ph-tpy = 4'-phenyl-2,2':6',2''-terpyridine (Mn1) for ultrasound (US) activated anticancer applications. The X-ray structure of Mn2 confirmed its distorted octahedral geometry. Mn1 and Mn2, for the first time, showed US-triggered release of CO and ROS generation (1O2 and •OH) in an aqueous solution from any Mn(I)-tricarbonyl complexes, indicating its potential for synergetic CO gas therapy and sonodynamic therapy. The above-mentioned in-solution chemistry was successfully translated into in vitro cellular models. These complexes showed unprecedented US-triggered toxicity against T-cell lymphoma and human breast cancer cells (IC50 for Mn2 < 1 μM) while were minimally toxic without US or against normal spleen cells. Mn2 was ca. 12 fold more anticancer active than Mn1, indicating that the ferrocene conjugation augmented the US sensitivity. The apoptotic sonotoxicity of Mn2 was due to US-promoted mitochondrial depolarization via ROS generation and CO release. The apoptosis was triggered by caspase 3 activation. This is the first report of Mn(I)-tricarbonyl-based sonosensitizers for cancer SDT. Overall, this study, for the first time, establishes the effectiveness of 3d metal carbonyls in SDT.

Isomerism in Phenyl 2‐Pyridyl Ketoxime Metal Complexes

AbstractThe octahedral complex [RhCl2(ppkoH)(ppko)] (1) was obtained from the reaction between RhCl3 and phenyl 2‐pyridyl ketoxime (ppkoH). Attempts to prepare the corresponding octahedral platinum compound from K2PtCl6 gave instead the square planar [Pt2+(ppko)2] (2), but when the halogen was changed to bromine, the octahedral [Pt4+Br2(ppko)2] (3) was formed. The crystal structures were determined by X‐Ray crystallography. All the compounds have two N,N‐chelating oxime ligands. In 1, one of them is deprotonated, while in 2 and 3 both ligands are deprotonated. Compounds 1 and 3 have two halogen ligands in trans position. In 1 the oxime groups are situated mutually in cis position with an intramolecular hydrogen bond between the two N−O(H) groups. The formation of 2 involves reduction of the platinum metal and the complex has oximes in trans position to each other. Compound 3 has an all‐trans geometry. Since octahedral and square planar compounds have a possibility to isomerism, we studied the relative stability of different geometries by DFT calculations. A mixture of isomers is likely to be formed in the reactions, but the most stable form was found to crystallize. The properties of the electron density in the preferred isomers were also investigated via QTAIM methods.

Structures and NMR Solution Dynamics of Diorganotin Complexes with Bulky Quadridentate Salen‐ and Salphen‐Type Schiff Bases (N2O2) Incorporating Diazenylpyridyl Side Arms

AbstractA series of six complexes [n‐Bu2Sn(L1)]⋅S (S=Benzene/toluene, mixed/partial) (1), [Ph2Sn(L1)]n⋅S (S=Benzene) (2), [Bz2Sn(L1)] (3), [n‐Bu2Sn(L2)]n (4), [Ph2Sn(L2)] (5) and [Bz2Sn(L2)] (6) were synthesized using diorganotin(IV) oxide precursors and two new bis‐Schiff bases containing N2O2 donor atoms. The Schiff bases, H2L1 and H2L2, were prepared by reacting ethane‐1,2‐diamine or benzene‐1,2‐diamine with 2‐hydroxy‐5‐(pyridin‐3‐yldiazenyl)benzaldehyde in absolute ethanol. Compounds 1–6 were characterized by IR and NMR spectroscopies, as well as by solid‐state single‐crystal X‐ray diffraction (except for 3 and 6). In all the complexes the bis‐Schiff bases occupy the equatorial positions and the R groups are in axial sites. However, while 1 and 5 are discrete molecules where the tin atoms adopt distorted octahedral geometries, 2 and 4 are monoperiodic polymers with the metal cations in pentagonal bipyramidal environments. Although solid state crystallographic results revealed asymmetrical molecular configurations, solution NMR studies proved symmetric arrangements for all the compounds. Tin NMR spectroscopy confirmed that all complexes are six‐coordinate in solution, despite variations in solid‐state coordination. Further analysis using Hirshfeld surface and fingerprint plots provided insights into intermolecular interactions in compounds 1, 2, 4, and 5. This comprehensive study underscores the structural diversity and solution‐state dynamics of organotin(IV) complexes synthesized using novel Schiff bases.

Design, characterization, and bioactivity evaluation of novel symmetrical N,N'-benzene-1,2-diylbis[1-(2-chloroquinolin-3-yl)methanimine] based metal complexes

This study presents the synthesis and characterization of two novel metal complexes derived from the symmetrical Schiff base N,N'-benzene-1,2-diylbis[1-(2-chloroquinolin-3-yl)methanimine] (OBCQ), coordinated with Nickel(II) (NiOBCQ) and Copper(II) (CuOBCQ). The structural elucidation of these complexes was achieved through a comprehensive suite of analytical techniques, including elemental analysis, UV–visible spectroscopy, mass spectrometry, infrared spectroscopy, magnetic susceptibility, conductivity measurements, and thermal analysis. The data confirm that both NiOBCQ and CuOBCQ adopt octahedral geometries, formulated as [Ni(OBCQ)(H₂O)₂(Cl)₂] and [Cu(OBCQ)(H₂O)₂(Cl)₂], respectively. Density Functional Theory (DFT) calculations were employed to validate the molecular structures and explore the quantum chemical parameters of OBCQ and its metal complexes. Additionally, in vitro assessments of anti-inflammatory and antioxidant activities revealed enhanced bioactivity for the metal complexes compared to the free OBCQ ligand. Molecular docking studies against key proteins (5IKT for Human Cyclooxygenase-2 and 5IJT for Human Peroxiredoxin 2) highlighted strong binding affinities and molecular interactions, suggesting that OBCQ and its metal complexes hold significant promise as novel therapeutic agents with multifaceted biological activities.

Five novel Pb/Zn/Co metal-organic frameworks using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and carboxylate ligands: Synthesis, characterization, DFT calculation and catalytic PMS degradation of RhB

Five new metal-organic frameworks (MOFs), namely {Pb(atpt)(3-bpd)0.5}n (1); {Co(cbz)2(3-bpd)(H2O)2·2H2O}n (2); {Co(imdc)(3-bpd)(H2O)·H2O}n (3); {Co(tdca)(3-bpd)(H2O)2·DMF}n (4); {Zn(tdca)(3-bpd)(H2O)2·DMF}n (5), were assembled with metal ions Pb²⁺, Zn²⁺, and Co²⁺ using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpd) as the main ligand, combined with 2-aminoterephthalic acid (H2atpt), 4-cyanobenzoic acid (Hcbz), 4,5-imidazoledicarboxylic acid (H2imdc), and thiophene-2,5-dicarboxylic acid (H2tdca) as auxiliary ligands via hydro/solvothermal methods. Their molecular structures were analyzed by single-crystal X-ray diffraction and characterized by FT-IR and PXRD. Complex 1 has a three-dimensional structure with a hepta-coordinated, semi-directed {PbNO6} metal center. The central metal ions in complexes 2–5 exhibit a six-coordinated {MN2O4} (M = Co or Zn) octahedral geometry. In complex 2, the carboxylate ligand does not function as a bridging ligand, resulting in a 1D chain structure, while complexes 3- 5 extend into 2D layered structures. Thermogravimetric analysis indicates good thermal stability for complexes 1–5. Then, the prepared complexes were used as catalysts to degrade Rhodamine B (RhB) during the monopersulfate (PMS) activation. Complexes 3 and 4 demonstrated significant efficiency, achieving degradation rates of 93.61 % and 98.56 % within 10 min. Radical scavenging experiments and EPR analysis identified that the activation of PMS for dye degradation by the two catalysts occurs through both radical and non-radical pathways, with SO4•− and •OH radicals being the dominant species. Density functional theory (DFT) calculations explained the superior catalytic performance of complex 4 compared to complex 3.

Supramolecular architectures, Hirshfeld surfaces analysis, spectroscopic, computational and photovoltaic properties of nickel(II) binary and ternary complexes of N-phenethyl-iminodiacetate (2-) chelate

The bluish-green color nickel(II) binary and/or ternary compounds have been isolated from the solution of stoichiometric reaction between Ni(II) hydroxy-carbonate and N-phenethyl-iminodiacetic acid (H2pheida) chelating ligand in aqueous media with compound (2); [Ni(pheida)(Him)3]·4H2O and without imidazole compound (1); [Ni(pheida)(H2O)3]. The crystal pattern of binary compound [Ni(pheida)(H2O)3] (1) differs from the related tetra-hydrated ternary complex of [Ni(pheida)(Him)3]·4H2O (2) can be attributed to the presence of stronger N-(Him) spacer of imidazole ligand. The compounds reported herein, have been characterized by means of elemental analysis, FTIR, UV–vis, TGA and X-ray crystallography. Moreover, the distinctive inter-molecular forces particularly H-bonding interactions, 2D fingerprint plots and supramolecular architecture have been studied using Hirshfeld surface analysis. The nickel(II) binary and ternary complexes (1) and (2) show distorted octahedral geometry around the Ni(II) ion of the type 1 + 2 + 2 + 1 imposed by 3d8 electronic configuration with degenerate fully and half occupied t2g6 and eg2 orbitals respectively. The higher John-Teller distortion has been observed for complex (2) than that of complex (1). The IDA arm of chelate adopted fac-NO2 conformation in both complexes (1) and (2). Moreover, the photovoltaic properties as semiconducting nature for ligand and their corresponding Ni(II) complexes were estimated using Tauc’s equation, αhν = A(hν-Eg)r, where r = ½ for indirect and 2 for direct electronic transitions through UV–vis absorption data. The indirect and direct electronic transition bandgap (Eg) calculated for complex (1) is 2.0 and 3.07 eV respectively. Similarly, 2.55 and 4.39 eV respectively measured for complex (2).

Two New 2p–3d Metal Complexes with a Nitronyl-Nitroxide Ligand Derived from o-Vanillin: Synthesis, Crystals Structures and Magnetic Properties

Two new 2p–3d complexes, (Et3NH)[ML(hfac)2], have been obtained using the nitronyl-nitroxide radical (HL) derived from 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (M = Mn 1; Co 2). The two compounds are isomorphous and their structures consist of anionic mononuclear species, [M(hfac)2L]−, M = Mn 1; Co 2, and triethylammonium cations, Et3NH+. The metal ions adopt an octahedral geometry, being coordinated by phenoxido and aminoxyl oxygen atoms from the ligand and four oxygen atoms from the hexafluoroacetylacetonato (hfac−) ligand. The cryomagnetic behaviors of the two compounds reveal relatively strong antiferromagnetic M(II)-Rad interactions (JMnRad = −191 cm−1, JCoRad = −166 cm−1 with H = −JSMSRad). The EPR spectra (X- and Q-band) of compound 1 below 70 K show the characteristical features of a S = 2 spin system with zero field splitting terms of D = 0.26 cm−1 and E = 0.031 cm−1.

Crystal structure of catena-poly[[diaquadiimidazolecobalt(II)]-μ2-2,3,5,6-tetrabromobenzene-1,4-dicarboxylato

The asymmetric unit of the title compound, [Co(C8Br4O4)(C3H4N2)2(H2O)2] n or [Co(Br4bdc)(im)2(H2O)2] n , comprises half of CoII ion, tetrabromobenzenedicarboxylate (Br4bdc2−), imidazole (im) and a water molecule. The CoII ion exhibits a six-coordinated octahedral geometry with two oxygen atoms of the Br4bdc2− ligand, two oxygen atoms of the water molecules, and two nitrogen atoms of the im ligands. The carboxylate group is nearly perpendicular to the benzene ring and shows monodentate coordination to the CoII ion. The CoII ions are bridged by the Br4bdc2− ligand, forming a one-dimensional chain. The carboxylate group acts as an intermolecular hydrogen-bond acceptor toward the im ligand and a coordinated water molecule. The chains are connected by interchain N—H...O(carboxylate) and O—H(water)...O(carboxylate) hydrogen-bonding interactions and are not arranged in parallel but cross each other via interchain hydrogen bonding and π–π interactions, yielding a three-dimensional network.

Selective Metal‐Coordinated Nanodrugs Based on Thiazine Moiety for Anticancer Therapeutics: Spectroscopic, Theoretical, and Molecular Docking Studies

ABSTRACTThe current study involved production, comprehensive structural analysis, and physicochemical characterizing of two distinctive complexes namely, Cu(TBH) and Zn(TBH); TBH donor ligand: N′‐(1‐(3,6‐dihydro‐4‐hydroxy‐2,6‐dioxo‐2H‐1,3‐thiazin‐5‐yl)ethylidene)‐2‐hydroxybenzohydrazide) using a wide range of analytical methods, including elemental analysis, UV–Vis, FT‐IR, and 1HNMR spectrometry, molar conductivity and magnetic susceptibility measurements, and thermal analysis. According to the findings, chelation can occur through O, N, and O donor atoms of monoanionic chelator for generating mono‐nuclear chelates with tetrahedral geometry for Cu (II) and octahedral geometry for Zn (II). The anticarcinogenic ability of TBH chelator and its coordinated compounds against human liver cancer (HepG‐2) was investigated. The Cu(TBH) complex was found to have selective and promising anticancer activity against a liver cancer cell line, with lower IC50 (liver carcinoma cell line) and higher IC50 (normal human cell line) values than other produced compounds and standard drugs. Utilizing DFT computations, the molecular structures of the TBH and its complexes were verified, offering a detailed understanding of their quantum chemical characteristics. A quantitative structure–activity relationship (QSAR) model, which illustrates the association between DFT‐computed descriptors and biological activities pIC50, was also created using multiple linear regression (MLR) on the synthesized compounds as anticancer medicines. Additionally, there are no issues with the produced compounds' oral bioavailability according to (ROF) Lipinski's rule of five. Furthermore, docking studies of the synthesized TBH chelator and its chelates with CDK2 kinase have been performed to validate the biological findings. According to our findings, the novel Cu(TBH) nanodrug exhibits considerable cytotoxic activity, prompting further study into its pharmacological profile and exploring its potential in drug development.

Solvent- and Concentration-Induced Topological Transformation of a Ruthenium(II)-Based Trigonal Prism to a Triply Interlocked [2] Catenane.

Synthesis of interlocked supramolecular cages has been a growing field of interest due to their structural diversity. Herein, we report the template-free synthesis of a Ru(II) triply interlocked [2] catenane using coordination-driven self-assembly. The self-assembly of a triazine-based tripyridyl donor L (2,4,6-tris(5-(pyridin-4-yl)thiophen-3-yl)-1,3,5-triazine) with a dinuclear Ru(II) acceptor M (Ru2(dhnq)(η6-p-cymene)2)(CF3SO3)2) yielded two distinct structures depending on the solvent and concentration. In methanol, a triply interlocked metalla [2] catenane (MC2) was formed, whereas in nitromethane, a non-interlocked cage (MC1) was obtained. The non-interlocked cage MC1 was gradually converted to MC2 in nitromethane by the increase in the concentration of cage MC1 from 0.5 to 9 mM. The interlocked cage (MC2) was stable after formation and was unaffected by the change in concentration. Notably, the free cage (MC1) exhibited host-guest interactions with polycyclic aromatic aldehydes, stabilizing the non-interlocked structure even at higher concentrations. In contrast, the triply interlocked [2] catenane (MC2) remains stable due to self-penetration and does not encapsulate guest molecules. This work showcases the stimuli-induced irreversible structural transformation of a triangular prismatic cage to its triply interlocked [2] catenane by employing metal-ligand coordination chemistry.