Template Condensation Research Articles

Chiral Homodinuclear Dysprosium Macrocyclic Complexes with Single‐Molecule Magnetic Behaviours

AbstractA pair of enantiomerically chiral dysprosium homodinuclear complexes: [(acac)4Dy2(R,R,R,R‐L)] (R‐Dy) and [(acac)4Dy2(S,S,S,S‐L)] (S‐Dy) (Hacac=acetylacetone) have been synthesized based on macrocyclic chiral ligands (R,R,R,R‐H2L or S,S,S,S‐H2L), derived from the [2+2] template condensation of 4‐tert‐butyl‐2,6‐diformylphenol, dysprosium acetylacetonate and (1R,2R)‐/(1S,2S)‐1,2‐cyclohexanediamine, respectively. Circular dichroism spectra confirms their enantiomeric chirality. Single‐crystal structures show two crystallographic independent dysprosium(III) ions have square antiprismatic coordination with different D4d local symmetry. Furthermore, the selected R‐Dy complex owns the slow magnetic relaxation behaviour with the ferromagnetic Dy3+⋅⋅⋅Dy3+ coupling.

Eu(III) complexes derived from 2-quinolinecarbohydrazide Schiff base ligand, relations between structure and luminescence properties

A series of Eu(III) complexes were obtained following the template condensation of 2-quinolinecarbohydrazide and 2,6-diacetylpyridine, namely: [Eu(H2pbqh)(NO3)3]·MeOH (1), [Eu(Hpqh)(NO3)3]·2MeCN (2), [Eu(H2pbqh)(SCN2)(MeOH)2](SCN) (3) and [Eu2(pbqh)2(NO3)2(H2O)2]·2.5MeOH (4). The structures of complexes and a new H2pbqh ligand (N',N'''-((1E,1′E)-pyridine-2,6-diylbis(ethan-1-yl-1-ylidene))bis(quinoline-2- carbohydrazides)) were elucidated by single-crystal X-ray diffraction. H2pbqh coordinate pentadentate ONNNO and forms mononuclear complexes 1 and 3. The bis-deprotonated ligand pbqh2- act as hexadentate/bridging mode generates the binuclear complex in 4. The partially condensed ligand Hpqh, tetradentate ONNO, was recorded in complex 2. The crystallographic results reveals that the coordinated H2pbqh/Hpqh ligands and Eu3+ cation form a planar structure in these complexes and nitrate anions coordinate chelate, completing the coordination sphere of Eu3+. The solid state photoluminescent emission was investigated highlighting the nitrate complexes 1 and 2 that exhibit red intense luminescence (λmax = 618 nm). Moreover, the computational calculations reveal different pathways of energy transfer from ligand to Eu3+ electronic states explaining the luminescent behavior.

Trivalent transition metal ion mediated template synthesis: In silico molecular docking, DNA binding, antimicrobial evaluation and DFT studies

In order to reduce the chances of multiple drug resistance, there is an urgent requirement for the designing of new antimicrobial agents. In this current research, series of novel hexaazamacrocyclic trivalent transition metal complexes of ChromiumIII and IronIII have been prepared by adopting the pathway of metal ion mediated template condensation. The newly synthesized macrocyclic complexes were analyzed by Infra-Red Spectroscopy, Carbon-Hydrogen-Nitrogen analyzer, UltraViolet–visible, Powder X-Ray Diffraction, Electron Paramagnetic Resonance, Magnetic Susceptibilities, Molar conductance, Electron Spray Ionisation-Mass Spectrometry and Thermogravimetric analysis techniques. The electro-lytic behaviour of the complexes was suggested by conductance (molar) values. All the complexes (T7-T12) can be formulated or represented as [MLX] X2·yH2O, where M = FeIII, CrIII and L is the macrocyclic ring resulting from 1,8-diaminonaphthalene and succinimide and X = NO3−, Cl−, CH3COO− and y = 1 or 2. All the macrocyclic complexes have been anticipated to have a penta coordinated square pyramidal shape using several physico-analytical approaches. Monomeric nature of the complexes was confirmed by CHN analysis and mass spectral data. Powder X-Ray Diffraction studies were carried out for interpreting the crystallinity of the complexes. Density Functional Theory studies were performed for energy optimization and theoretical calculations of UV & IR. The DNA interaction studies showed intercalative mode of binding is present in the newly designed complexes with the DNA. In addition to these, all the metal complexes were screened for their antibacterial and antifungal activity against pathogenic strains of bacteria and fungi, Complex T7 has effective bactericidal action against B. cereus and E. coli. Molecular docking studies were also performed on SARS Cov-2 and Mycobacterium tuberculosis. The used proteins are NSP15 Endoribonuclease from SARS CoV-2 and DNA of Mycobacterium tuberculosis H37Rv. The results revealed that complex T10 is having good binding affinity against DNA of Mycobacterium tuberculosis H37Rv.

Tetraaza macrocyclic complexes of Cu(II), Co(III) and Ni(II) derived from template condensation of 2,6-pyridinedicarbohydrazide and 2,6-diacetylpyridine: Stability investigation and coloring properties on plastics

Completely conjugated 14-membered ring hexaaza ligand complexes of Cu(II), Co(III) and Ni(II) were synthesized by the template cyclo-condensation reaction of 2,6-diacetylpyridine and 2,6-pyridinedicarbohydrazide: [Cu(HL)Cl]·1.35H2O (1), [Cu(HL)Br]·CH3OH (2), [Cu(L)(H2O)]·4H2O (3), [Co(HL)Cl2]·CH3OH (4), (H3O)[Co(H2L)Cl2][Co(HL)Cl2]Cl2·H2O (5), [Co(HL)(SCN)2]·CH3OH (6), [Ni(L)]·3H2O (7) and (H3O)[Ni(L)]Cl·H2O (8). The structure of all complexes derived from this novel diprotic macrocyclic ligand H2L (5,7-dimethyl-3,4,8,9-tetraaza-1,6(2,6)-dipyridinacyclodecaphane-4,7-diene-2,10-dione) were determined by single crystal X-ray diffraction method. The tetraaza 14-membered conjugated macrocycle is N4-tetracoordinated to metal, adopts an essentially planar configuration and forms four fused metallocycles rings, two five-membered and two six-membered chelates. The structures of the studied complexes reveal three isomers out of three possible: with a 5-6-5-6 order of alternation of metallocycles for 1–6, the 5-5-6-6 isomer in 8 and the coexistence of two different isomers with 5-5-6-6 and 6-6-5-5 alternation of metallocycles in 7. Based on the protonation state of the macrocyclic ligand, four forms of the ligand have been registered: bis-deprotonated L2− (compounds 3, 7 and 8), monodeprotonated HL− (1, 2 and 4), neutral H2L (5) and for compound 6 tautomeric (amide → imidic acid) HL− form. The organisation of crystal structures 1–8 depends on the nature of the metal and the composition of the solvents and outer-sphere ions, but shows clear common features for the same type of metal. The hydrolytic study demonstrated a high stability of the Co(III) and Ni(II) complexes in acidic solutions and the most thermally stable are the complexes 3 and 7 with the limit of 350 °C for Ni(II) complex. Testing of the coloring properties of the [Ni(L)] (8) complex on plastics indicates a high coloring efficiency, especially for polyamide polymers.

Mononuclear nickel(II) and copper(II) coordination compounds with ligands based on acetyl(benzoyl)acetone S-methylisothiosemicarbazones and 8-quinolinecarboxaldehyde. Synthesis and crystal structure

Template condensation of S-methylisothiosemicarbazones of acetyl- or benzoylacetone with 8-quinolinecarboxaldehyde in the presence of nickel(II) and copper(II) ions gave four new mononuclear coordination compounds [NiL1]I (I), [CuL1I] (II), [NiL2]I (III) и [CuL2I] (IV). The chemical composition of the products was confirmed by elemental analysis, IR spectroscopy, and mass spectrometry, and the crystal structure of compounds I and II was determined by X-ray diffraction analysis (CCDC no. 2266386, 2266387). X-ray diffraction study revealed a square planar coordination environment of the central ion of the cationic Ni(II) complex and square pyramidal geometry for the molecular Cu(II) complex.

Synthesis, Characterization and in vitro Antimicrobial Activity of Organotellurium Decorated 10-Membered Tetraazamacrocyclic Complexes of Cobalt(II)

Three novel organotellurium decorated 10-membered tetraazamacrocyclic complexes of Co(II) were synthesized using template condensation of 1,1-diiodo-1-telluracyclopentane, 1,1-diodo-2-methyl-1-telluracyclopentane and 1,1-diiodo-1,1-diethyltellurium(IV) with 1,2-diaminopropane and cobalt dichloride hexahydrate in dry methanol in 2:2:1 molar ratio. The characterization of the synthesized cobalt(II) complexes was carried out using elemental analysis, spectroscopic studies (IR, proton NMR & proton decoupled carbon NMR) and molar conductance measurements. The results of these studies suggested that the complexes may be formulated as [CoLCl2] where L = {C4H8Te-(NHCH2CH(CH3)NH)}2, {C4H7(CH3)Te(NHCH2CH(CH3)NH)}2 and {(C2H5)2Te(NHCH2CH(CH3)NH)}2. The synthesized complexes were also screened for antimicrobial activity using broth microdilution and agar disc diffusion methods.

Stabilization of a given type of 3d-metal-centered cage complexes via encapsulation and/or hydrogen abstraction

Template condensation of nioxime as a chelating synthon and tolylboronic acid as a cross-linking agent in the presence of M(II) or M(III) salts (M = Fe, Mn) gave the regular metal(II) clathrochelates. That with Cr(II) or Cr(III) salts afforded the stable chromium(III) macrobicyclic anion-radical with two alicyclic and one ortho-benzoquinonedioximate chelate fragments.

Unexpected formation of FeIIFeIIIFeII- and FeIIFeIIFeII-trinuclear hexapyridineoximate helicates: synchrotron single-crystal X-ray structures

Template condensation of 2-acetylpyridineoxime with butyl ester of 1,3-propanediboronic acid in the presence of iron(II) affords a poorly separable mixture of complex products. Similar results were observed when Fe3+ ions were used for cross-linking in place of the diboronic acid. Prolonged crystallization of these mixtures gave crystals of perchlorate salts of a FeIIFeIIIFeII-trinuclear hexapyridineoximate cation and of an analogous FeIIFeIIFeII-intracomplex that crystallize with chloroform and dichloromethane solvent molecules, respectively. Both complexes were characterized by synchrotron single-crystal X-ray diffraction (XRD) experiments. The Fe–N distances of the two ‘terminal’ iron cations are virtually the same between these trinuclear complexes and unambiguously support assignments of oxidation number +2 and low-spin state (S = 0). The centers of the FeN6 -coordination polyhedra adopt geometries resembling trigonal antiprisms with distortion angles φ of approximately 40°. The FeO6 -coordination polyhedra possess an almost ideal Oh geometry with φ close to 60°. Each of these iron(II) or iron(III) µ3 -metallocenters acts as a bifunctional Lewis acid that cross-links two pseudoclathrochelate entities, formed by the ‘terminal’ iron(II) ions, to give an almost linear (the corresponding intramolecular Fe(2)…Fe(1)…Fe(3) angles are close to 180°) helical cation or intracomplex.

Effects of solvatomorphism, the nature of a chelating ligand synthon and a counterion on the single crystal XRD structure and SMM properties of paramagnetic monocapped cobalt(II) tris-pyrazoloximates.

A series of monocapped cobalt(II) tris-pyrazoloximates was obtained through the template condensation of the corresponding pyrazoloxime, phenylboronic acid and a suitable cobalt(II) halogenide. Comparing 3-acetylpyrazoloxime versus its methine-containing homolog, the former produced cobalt(II) clathrochelates in substantially higher yields due to the electron donating effect of the methyl substituent, increasing the N-donor ability of its oxime group. Their less N-donor analog with the electron acceptor trifluoromethyl group did not form cobalt(II) complexes of this type. In all their solvent-free and solvent-containing crystals, the encapsulated cobalt(II) ion adopted a high-spin state, as gauged by the Co-N bond lengths of 2.112(4)-2.188(9) Å, and was located almost in the center of its CoN6-coordination polyhedron. Their CoN6-polyhedra had an almost ideal trigonal-prismatic (TP) geometry with distortion angles φ below 4°. This TP-like geometry was assisted by hydrogen bonding between their NH groups and the apical counterion. The absence of methyl groups makes them close to an ideal TP. In contrast, stronger N-H⋯Cl hydrogen bonds occurred in the methyl-containing complex, while the Co-N bond lengths stayed the same at 2.144(2) Å on average. In its solvates with benzene, chloroform and acetone, there is a clear tendency for φ to decrease from 2.7(3)° to 0.47(13)°. The comparable effects of the ribbed methyl substituents, the cross-linking counterion and the lattice solvent on their molecular geometry were observed; the larger the distortions from an ideal TP geometry, the stronger the hydrogen bonds to the corresponding apical halogenide anion. The analysis of the experimental AC- and DC-magnetometry data for their fine-crystalline samples suggests that the passing from the derivative of the methyl-substituted synthon to that of its methine-containing homolog caused a substantial decrease in the magnetic susceptibility value χT and an increase in the QTM contribution to the magnetic relaxation. The effect of a cross-linking halogenide counteranion on the Orbach remagnetization barrier is greater than that of the solvatomorphism of their crystals.

SYNTHESIS AND PROPERTIES OF PERIPHERALLY AND NONPERIPHERALLY SUBSTITUTED ZINC AND MAGNESIUM PHTHALOCYANINES BASED ON 3/4-(4-BROMO-2-((4-METHOXYPHENYL)DIAZENYL)PHENOXY)PHTHALONITRILE

The work describes the optimization of the procedure for the synthesis of 4-bromo-2-methoxyphenyldiazenylphenol, which is used as a nucleophile in the presence of 3- and 4-nitrophthalonitriles. The resulting 3-(4-bromo-2-((4-methoxyphenyl)diazenyl)phenoxy)- and 4-(4-bromo-2-((4-methoxyphenyl)diazenyl)phenoxy)phthalonitriles were used for template condensation with magnesium or zinc acetate. Methods for isolating and purifying the synthesized compounds are described. The structure and composition were confirmed using IR, 1H NMR and electron spectroscopy. Peripheral functionalization of macrocycle by a conjugate azochromophore fragment gives molecules phthalocyanine with special optical properties. This class of phthalocyanines containing an additional chromophore system in their composition is attractive for potential use not only as pigments and dyes traditional for phthalocyanine compounds, but also as chemical sensors, dye-sensitized solar cells and photosensitizers for PDT. The resulting nitriles and phthalocyanine complexes dissolve in chloroforms, toluene, THF, and DMF. The influence of the substituent location on the spectral properties of the obtained metal complexes (Zn, Mg) in organic solvents has been studied. For non-peripherally substituted metal phthalocyanines, acid-base properties are studied. To observe and study the acid-base effect, spectrophotometric titration of the trifluoroacetic acid complex in toluene is used. It is shown that the magnesium complex is more basic than the zinc complex. In this work, the luminescent properties are also studied and the quantum yields of singlet oxygen formation for synthesized complexes in THF are determined. The influence of the substituent location on the quantum yield of fluorescence, as well as on the generation of singlet oxygen, is noted in the work.

Trivalent Tetraazamacrocyclic Complexes of Cr(III) and Fe(III): Synthesis, Characterization and Antimicrobial Evaluation

A novel series of macrocyclic compounds, [M(C37H36N4)X]X2; where M = Cr(III) and Fe(III); X = Clˉ, NO3ˉ, CH3COOˉ, have been synthesized by using the template condensation between 3,4-diaminotoluene, dibenzoyl methane and dimedone in the presence of chromium(III) and iron(III). Various physio-chemical studies were used to characterize these complexes including PXRD, magnetic susceptibility, elemental analysis, electronic, IR and mass spectroscopy. These studies suggested that all the metal complexes have a five-coordinated square pyramidal geometry around the metal ion. The molar conductance values of these complexes in the range of 168-140 ohm-1cm2mol-1 indicated the electrolytic nature of these complexes. Furthermore, the antibacterial and antifungal behavior of these complexes was also examined by using different microbial strains i.e. Bacillus subtilis, Escherichia coli and Candida albicans. In addition to this, the results of antibacterial and antifungal of complexes were compared with commercially available antibacterial and antifungal drug i.e. ciprofloxacin and Amphotericin B, respectively.

Synthesis and Structure of the Dicarboxyl-Terminated Iron(II) Tris-Glyoximates with Linear and Angular Geometry of their Molecules

Template condensation of the chelating α-dioximate ligand synthon—glyoxime and the appropriate cross-linking agent—monofunctionalized boronic (3-carboxyphenylboronic or 4-carboxyphenylboronic) Lewis acid in a boiling nitromethane as a solvent on the iron(II) ion as a matrix afforded the dicarboxyl-terminated iron(II) tris-glyoximates with functionalizing meta- and para-substituents in their apical boron-based aromatic fragments. The composition and structure of these macrobicyclic complexes were confirmed using elemental analysis, UV-vis, 1H and 13C{1H} NMR spectra. Their crystal and molecular structures were obtained by the single crystal X-ray diffraction experiments. Asymmetric units of their crystals contain, besides of a clathrochelate molecule, two solvate molecules, which form hydrogen bonds with its functionalizing carboxyl groups. The C–O bond lengths in these terminal groups and a possibility of localization of hydrogen atoms on the difference Fourier maps clearly demonstrate that the formation of such associates does not include a deprotonation of the macrobicyclic complex and its intracomplex molecules remain neutral. The encapsulated iron(II) ion in their molecules occupies a centre of its FeN6-coordination polyhedron. Its geometry is intermediate between a trigonal prism (TP, the distortion angle φ = 0°) and a trigonal antiprism (TAP, φ = 60°); the values of φ are equal to 17.1 and 18.9°, respectively. Fe–N distances vary from 1.901(2) to 1.924(2) Å, thus suggesting a low-spin diamagnetic state of the encapsulated iron(II) ion. The C=N bonds in the donor oxime groups are shortened, while the С–С bonds in the chelating glyoximate fragments are elongated, as compared with those in their aliphatic analogs. Free rotation of the apical aromatic substituents at the cross-linking boron atoms around the ordinary B–C bonds caused the absence of their coplanarity. The intramolecular distances С···С between the terminal carboxyl groups in the apical cross-linking fragments are equal to 15.693(4) and 17.888(3) Å for the clathrochelate meta- and para-isomers, respectively. The aforementioned rotation allows to achive an angular geometry of the prospective meta-dicarboxyloclathrochelate ligand with a formation of ∠C···Fe···C close to 145° between its terminal O‑donor carboxyl groups. This complex can play a role of both the angular and linear 3D-ligands, while its clathrochelate para-substituted isomer seems to be the prospective linear metalloligand.

Tetraquinoxalinoporphyrazine – π-extended NIR-absorbing photosensitizer with improved photostability

A novel ionogenic water-soluble zinc complex with π-extended ligand – tetraquinoxalinoporphyrazine bearing eight benzoate groups – ZnQPz(COONa)8 was synthesized by template condensation of a new building block, dipentyl 4,4'-(6,7-dicyanoquinoxalin-2,3-diyl)dibenzoate followed by alkaline hydrolysis of ester groups. The photophysical properties of the complex were studied and a significant bathochromic shift of the Q-band by 100 nm was observed as compared to conventional phthalocyanine complexes. However, in contrast to other NIR-absorbing π-extended derivatives with similar optical properties, ZnQPz(COONa)8 showed a high degree of photostability – its photobleaching rate in DMSO was about 3 times lower than that of the zinc tetra-15-crown-5-naphthalocyanate Zn[(15C5)4Nc]. The improved photostability together with the ability to generate singlet oxygen (ФΔ = 0.65 in aqueous DMSO) and absorb light in the near infrared region makes quinoxaline-porphyrazine a good candidate for use in photodynamic therapy.

One-pot synthesis, characterization, photocatalytic activity and biological studies of Co(II), Ni(II) and Cu(II) complexes of a tetraazamacrocyclic Schiff base

Template condensation between pentane-1,5-dial and triethylenetetramine in the presence of divalent metal salts in methanolic solution resulted in mononuclear 15-membered tetraazamacrocyclic Schiff base metal complexes, [M(C11H22N4)X2], where M = Co(II), Ni(II) and Cu(II), X = Cl− and C11H22N4 is the tetradentate macrocyclic ligand. The bonding and overall geometry of the complexes are inferred through elemental analysis, FT-IR, UV–vis, 1H/13C NMR, ESI-mass, molar conductance, magnetic susceptibility and TG measurements. On the basis of the absorption bands in UV–vis spectra and magnetic moment analyses, a six-coordinate octahedral geometry is proposed for all the metal complexes. The formulation of the metal chelates is compatible with the thermal decomposition profiles. Photocatalytic efficiency of the macrocyclic Ni(II) complex was studied using solar water-splitting. The in vitro antimicrobial activity of metal complexes has been tested against certain bacterial and fungal species. The scavenging ability of DPPH free radicals was used to test the antioxidant activity of the complexes. In addition, MTT assay was used to assess the cytotoxicity of Cu(II) chloro complex against L929 mouse fibroblast cell lines.

Gamma ray irradiated binuclear and mononuclear transition metal complexes with polydentate ligand: Template synthesis, spectral, XRD, morphology, solid electrical conductivity and antimicrobial activity

In this work, new binuclear Fe(III), Ni(II) and mononuclear Cu(II) Schiff base complexes that obtained via template condensation of Fe(III), Ni(II) and Cu(II) chlorides with N1-(3-aminopropyl) propane-1,3-diamine and 1,3-diphenylpropane-1,3‑dione (1B, 2B, 3B), respectively were prepared and well investigated. The structure of the complexes was elucidated by means of microanalyses, various spectroscopic techniques (FT–IR, UV/Vis, X–ray diffraction), thermal (TG/DTG), molar conductivity and magnetic moment measurements, Fe(III), Ni(II) complexes have an octahedral structure, while Cu(II) complex adopts distorted square pyramidal geometry. To study γ– irradiation induced modifications, powder sample of these complexes was exposed to high energetic γ–ray irradiation at a dose of 20 kGy, (hereafter referred to as 1A, 2A, 3A, respectively). Physico-chemical properties of irradiated samples were also investigated by the aforementioned tools. The results revealed no remarkable change in the molar conductivity values and little shift of the peak position and the intensity for FT–IR and electronic spectra as a result of the distortion of lattice planes. Also, TG/DTG studies revealed decreasing in the thermal stability for all irradiated samples. From the powder XRD data for non-irradiated and γ–irradiated Ni(II) (2B, 2A) and Cu(II) (3B, 3A) complexes, average crystallite size (D) and dislocation density (δ) were calculated, the γ–irradiation resulted in decrease in the crystallite size for Ni(II) (2A) complex. The irradiated (3A) showed changes in the surface morphology compared to its non-irradiated one. The solid state electrical conductivity of non-irradiated and γ–irradiated Ni(II) complexes have been investigated. Furthermore, the non-irradiated samples (1B, 3B) and their γ–irradiated (1A, 3A) were assayed for their antibacterial property against Gram–positive as Staphylococcus aureus, Gram– negative as Escherichia coli and antifungal property against fungi as Candida albicans.

Synthesis, Characterization, Biological Activity and Molecular Docking Studies of Phthalic Acid based Macrocyclic Transition Metal Complexes

A novel series of macrocyclic complexes of [M(L)Cl2] (M = Co(II), Ni(II) and Cu(II), L = macrocyclic ligand) were synthesized by template condensation method using 3,4-diaminotoluene and phthalic acid in the presence of divalent transition metal ions e.g., Co(II), Ni(II) and Cu(II) in their chloride form. These synthesized metal complexes were fully characterized by spectroscopic techniques, namely UV-Visible, IR, ESR and ESI-MS. Their thermal behaviour was determined by TGA and DTA. Further these macrocyclic complexes were screened for antimicrobial activity against bacterial species (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli) and fungi (Aspergillus niger and Candida albicans) and then compared against standard drug streptomycin and itraconazole, respectively. In addition to these the antioxidant activity of the macrocyclic complexes were also investigated through scavenging effect on the DPPH radicals. Finally, the biological potency of synthesized compounds was evaluated using Auto Dock Vina. All the synthesized macrocyclic complexes were found to be potent against bacterial and fungal species, which suggest their potential application as antibacterial and antifungal agents.

Preparation and structural characterization of 4-pyridylboron-capped iron(II) clathrochelates and their chemical transformations into hybrid metallo(IV)-phthalocyaninatoclathrochelate derivatives

Mixed boron,antimony-capped iron(II) tris-dioximate monoclathrochelates and their hybrid phthalocyaninatoclathrochelate derivatives, the molecules of which are decorated with the single N-donor 4-pyridyl group, were obtained using two different approaches, such as (i) a transmetallation (a capping group exchange) reaction of their antimony-capped macrobicyclic precursors, and (ii) the direct template condensation of the [Formula: see text] ion as a matrix. The obtained complexes were characterized using elemental analysis, 1H and [Formula: see text]C{1H} NMR, MALDI-TOF MS, and UV–vis spectra, and by the single-crystal X-ray diffraction experiments. Solution UV-vis spectra of 4-pyridyl-terminated iron(II) phthalocyaninatoclathrochelates can be described as a superposition of the spectrum of its metallocomplex precursor MIVPc and that of the iron(II)-encapsulating semiclathrochelate fragment. As follows from the X-ray diffraction data for the hybrid hafnium(IV)-capped tris-dimethylglyoximate pthalocyaninatoclathrochelate and its macrobicyclic boron,antimony-capped precursor, their [Formula: see text]-coordination polyhedra possess the geometry close to intermediate between a trigonal prism (TP) and a trigonal antiprism with the distortion angles [Formula: see text] of 20–30∘. Due to a non-equivalence of their capping fragments, it can be also described as a distorted truncated trigonal pyramid. [Formula: see text]-coordination polyhedron in the hybrid complex possesses the geometry of a capped TP. 4-Pyridylboron-capped pthalocyaninatoclathrochelates are proposed as prospective monodentate N-donor 3D-ligands for the design of various clathrochelate-based coordination assemblies, polytopic and polynuclear systems.

Biologically important 26-32-membered macrocyclic complexes of manganese (II): In situ one pot template synthesis (IOPTS), characterization and bio-efficacy

Twenty six to thirty two membered tetraazamacrocyclic complexes of manganese (II) have been synthesized by template condensation of MnCl2.4H2O with dicarboxylic acid (malonic, succinic, glutaric or adipic acid) and 1,8-diaminooctane in 1:2:2 molar ratios. The new products with octahedral geometry have been characterized by elemental analyses, molecular weight determinations, molar conductance, magnetic moment and spectral studies viz., infrared and electronic. On the basis of the spectral studies the binding sites are proposed as the nitrogen atom of the macrocycles. The formulation of the complexes as [Mn(Macn)Cl2] (where n = 1 - 4) has been established on the basis of chemical composition. To assess the growth inhibiting potential of the manganese (II) complexes biological screening has been undertaken.

Synthesis, Spectroscopic Characterization, Biocidal evaluation Molecular Docking & DFT Investigation of 16-18 membered Macrocyclic Complexes of Cobalt (II).

Antimicrobial, DFT, and Docking representation of Cobalt (II) macrocyclic complexes. The online version contains supplementary material available at 10.1007/s12039-022-02109-2.

Kinetics of the Template Synthesis and Acidic Decomposition of the Methylboron‐Capped Iron(II) Tris‐heptoximate: Dramatic Changes in a Series of Alicyclic α‐Dioximate Ligand Synthons

AbstractReaction of the template synthesis of the methylboron‐capped iron(II) tris‐heptoximate clathrochelate on Fe2+ ion as a matrix was found to proceed in the quantitative yield in diluted aqueous‐organic solutions. This complex is intensively colored in the visible range, whereas the initial ligand synthons are optically silent, thus allowing to photometric study the kinetics of its synthesis and acidic decomposition reactions. Template condensation of the corresponding chelating and capping ligand synthons gave a solid form of this macrobicyclic complex, which was characterized using modern spectral methods and by the single‐crystal X‐ray diffraction (XRD) experiment. Kinetic schemes and parameters of the aforementioned reactions for the methylboron‐capped clathrochelates, the derivatives of six‐ (H2Nx), seven‐(H2Gx) and eight(H2Ox)‐membered alicyclic α‐dioximes, are dramatically affected by their alicyclic ring size. If the general schemes of their formation persist, those for H2Nx and H2Gx contain a rate‐determining stage, whereas that for H2Ox has three initial consecutive stages with close rates. Passing from H2Nx to H2Gx caused a decrease in the synthesis reaction rates of their macrobicyclic derivatives by approximately three orders of magnitude. These kinetic effects were explained using the XRD data for the initial α‐dioximes and for their methylboron‐capped macrobicyclic derivatives.