Approaches are proposed for the synthesis of binuclear cationic copper(II) complexes [ Cu_2^II (BPA)2(μ-OH)2]2+ (BPA is 2,2'-bipyridylamine) (I) and [ Cu_2^II (Bipy)2(μ-OH)2(DMF)2]2+ (Bipy is 2,2'- bipyridyl) (III) stabilized by the closo-dodecaborate anion [B12H12]2–. The approaches are based on the use of precursor complexes Ph4P[CuI[B12H12]m (Ph4P is tetraphenylphosphonium) in the case of BPA and Et4N[Ag[B12H12]m (Et4N is tetraethylammonium) and [CuII2(Bipy)4(μ-CO3)]Cl2 in the case of Bipy as the starting reagents. The synthesis in the Ph4P[CuI[B12H12]m–BPA system was accompanied by the formation of a by-product, [Cu(BPA)2][B12H12]m (II), of known structure. The products were characterized by elemental analysis and IR spectroscopy. The structures of [ Cu_2^II (BPA)2(μ-OH)2][B12H12]·2DMF (I·2DMF) and [ Cu_2^II (Bipy)2(μ-OH)2(DMF)2][B12H12]·2DMF (III·2DMF) were determined by X-ray diffraction analysis.
The 1H NMR spectra of CDCl3 solutions of a broad series of lanthanide complexes with the general formula Ln(L)3(NO3)3 (where L = 4-(dodecyloxy)-N-octadecyl-2-hydroxybenzaldimine; Ln = La, Nd, Eu, Gd, Tb, Dy, Ho, Er, and Yb) at a concentration of ∼10–3 mol/L at Т = 300 K are detected and analyzed using Bleaney’s theory. The whole series of the compounds in a solution is proved to be isostructural, and the crystal field parameters are estimated.
Hydroxystibonium complex [(2,6-(OMe)2C6H3)3SbOH]I (I) was obtained by recrystallization of the product of iodination of tris(2,6-dimethoxyphenyl)stibine from wet pyridine. The reaction of benzene solutions of tris(2,6-dimethoxyphenyl)antimony dibromide and silver perchlorate followed by recrystallization from ethanol afforded complex [(2,6-(OMe)2C6H3)3SbOH]ClO4·0.5EtOH (II) with a similar antimony organic cation. Comparative characterization of the compounds was carried out using IR spectroscopy and X-ray diffraction methods. According to X-ray diffraction data (CCDC nos. 2 556 559 (I), 2 556 560 (II)), the tetrahedral [(2,6-(OMe)2C6H3)3SbOH]+ cations of the compounds have a structural similarity. The OSbC bond angles are 101.8(1)°–112.1(1)° (I), 98.3(1)°–110.6(1)°, 97.1(1)°–110.3(1)° (II); the CSbC angles are 104.8(1)°–115.1(1)° (I), 108.2(1)°–114.7(1)°, 105.3(1)°–118.2(1)° (II). The Sb–O and Sb–C interatomic distances are 1.910(3) Å (I), 1.914(3), 1.918(3) Å (II); and 2.073(3)–2.080(3) Å (I), 2.074(4)–2.089(3), 2.072(4)–2.083(4) Å (II).
A 2D Zn(II)-based MOF (Zn-MOF) named [Zn(bpydb)(bib)]n was solvothermally synthesized using 4,4'-(4,2'-bipyridine)-2,6-dibenzoic acid (H2bpydb) and 1,4-bis(imidazolyl)butane (bib). It crystallizes in the monoclinic P21/c space group with Zn2+ in a four-coordinate tetrahedral geometry. Elemental and FT-IR analyses verified high purity and successful framework formation. The Zn-MOF shows strong fluorescence at 388 nm (λex = 245 nm) with a red shift from LLCT, and good thermal stability up to 395°C. Fluorescence quenching tests reveal nearly 100
New dihalogenotin(IV) complexes with 3,6-di-tert-butyl-o-benzoquinone and diimine ligands, pyrazino[2,3-f][1,10]phenanthroline (DPQ) and dipyrido[3,2-a:2'3'-с]phenazine (DPPZ), are synthesized and structurally characterized. The complexes have the distorted octahedral coordination environment in which the catecholate and diimine ligands are mutually cis-oriented. The electronic absorption spectra of the synthesized compounds exhibit the charge-transfer bands between the donor catecholate and acceptor nitrogen-containing ligands in the range of 400–650 nm causing their intense color. The position of the maximum in the absorption spectra depends on the nature of the halogen substituent and extent of π-conjugation of the diimine ligand. The reaction of the starting 3,6-di-tert-butylcatecholatodichloridotin(IV) complex with 2,2'-azobis(pyridine) is accompanied by a complete two-electron transfer from the catecholate ligands to the nitrogen-containing ligand with the formation of the biradical binuclear system. An analysis of the absorption spectrum demonstrates a series of electronic transitions in a range of 700–1400 nm attributed to the charge transfer between the organic ligands of the complex.
Coordination compound [Mg(HKoj–)2]n is synthesized by the reaction of kojic acid (H2Koj) with magnesium acetate in an aqueous solution. The empirical formula of the synthesized compound is determined from the elemental and thermogravimetric analyses data. The thermal oxidative stability of magnesium kojate is studied by simultaneous thermal analysis in air. The molecular structure of the complex is discussed using spectral methods (NMR and IR spectroscopy) and studied in detail using X-ray diffraction (XRD) analysis (CIF file CCDC no. 2513260). Magnesium kojate is a coordination polymer with the chelate environment of the metal cation. The compound crystallizes in the triclinic symmetry group P1̅ .
New complexes [GdL3(NO3)3] (I) and [TbL3(NO3)3] (II) with asymmetric phosphine oxide were synthesized and studied. The Gd(III) complex was characterized by X-ray diffraction (CIF file CCDC no. 2 523 426). The luminescence spectra of the obtained complexes were studied. Substitution of one phenyl ring in TPPO with a methyl group yields ligand phosphine oxide (L) L with a reduced triplet energy ( 25 000 cm–1), which matches Latva’s optimal range for Tb(III) sensitization. Сomplex II exhibits bright green emission, confirming efficient energy transfer. Ligand L is thus proposed as an ancillary ligand for quenching solvent displacement in terbium diketonate and carboxylate complexes.
New coordination compounds of lanthanides(III) with N-oxide of nicotinate anion (1-oxidopyridin-1-ium-3-carboxylate anion) [Ln(NNO)(H2O)5]Cl2·H2O, where Ln = Gd (I) and Tb (II), and NNO = nicotinate anion N-oxide (C6H4NO3), are synthesized and characterized. The compounds are prepared by the reactions of lanthanide chlorides with nicotinic acid N-oxide in ethanol on reflux. The compositions and structures of the complexes are confirmed by the elemental analysis, IR spectroscopy, and X-ray diffraction (XRD) data. Complexes I and II are found by XRD to be isostructural and crystallize in the monoclinic crystal system (space group P21/n). The unit cell parameters for complex I are the following: a = 11.0963(3), b = 10.3399(3), c = 13.1766(4) Å, β = 112.666(1)°, V = 1395.05 Å3; and those for complex II are the following: a = 11.0659(3), b = 10.3196(2), c = 13.1580(3) Å, β = 112.576(1)°, V = 1387.44 Å3. The coordination spheres of the Gd (I) and Tb (II) atoms are formed by five water molecules and four oxygen molecules of four NNO ligands that act as bridging units binding lanthanide atoms into a dimer. The N-oxide and carboxylate groups of the ligands participate in the formation of coordination layers in the family of 011 planes. The chloride ions and molecules of water of crystallization involved in the formation of the framework bound via hydrogen bonds of the O(w)–H···Cl and O(w)–H···O(w) type are arranged between the layers.
The copper(II) perchlorate complex [Cu2(phendione)2L4](ClO4)4·3H2O (I) is synthesized from 1,10-phenanthroline-5,6-dione (phendione) and 1-(1H-benzimidazol-1-ylmethyl)-1H-1,2,3-benzotriazole (L). Complex I is characterized by elemental and thermogravimetric analyses, optical and IR spectroscopy, and single-crystal and phase X-ray diffraction analyses (XRD). The crystal structure of the complex is determined by single-crystal XRD: the compound is binuclear due to the bridging function of L, and the coordination number of the copper atom is five. The cytotoxic properties of the complex toward tumor cell lines А549 and MCF7 and nontumor human fibroblasts MRC5 are studied. The complex has cytotoxic activity in the micromolar concentration range exceeding that for cisplatin served as the reference.
This study demonstrates an approach to the targeted synthesis of heterometallic coordination polymers using bis(diphenylphosphoryl)ferrocene (dppfO2) as a cross-linker and mononuclear manganese(II) and zinc(II) cymantrenecarboxylates (OOCCym) as building blocks. This gave two coordination polymers [Mn2(µ-OOCCym)4(dppfO2)]n (I) and [Zn2(µ-OOCCym)4(dppfO2)]n (II), which were characterized by X-ray diffraction (CCDC nos. 2539856, 2539857), IR spectroscopy, and elemental analysis. According to X-ray diffraction data, compounds I and II were isostructural and consisted of binuclear zinc or manganese tetracarboxylates with a paddle-wheel structure cross-linked with dppfO2 to give 1D polymers.
The influence of the nature of the N-donor ligand (2,2'-bipyridyl, 1,10-phenanthroline, bathophenanthroline, 2,2':6',2”:6”,2”'-tetrapyridine, 4,4'-bipyridyl, and N-phenyl-ortho-phenylenediamine) on the compositions and structures of the Dy3+ pentafluorobenzoate (pfb) complexes is studied. The variation of the ligands or initial reagent ratio allows the preparation of both binuclear and mononuclear complexes, as well as coordination polymers. When using N-phenyl-ortho-phenylenediamine as an N-donor ligand, the dimerization occurs to form cation of (3-amino-10-phenylphenazin-2-ylidene)benzenaminium (L) in the coordination compound [Dy2(L)(pfb)7]n·3nMeCN. The synthesized compounds are characterized by single-crystal and phase X-ray diffraction (XRD) analyses, IR spectroscopy, and CHN analysis. The magnetic properties of the binuclear [Dy2(MeOH)2(phen)2(pfb)6] complex are studied in detail. The crystal packings of all synthesized compounds are stabilized by numerous noncovalent contacts π···π, C–F···π, and C–H···F.
The basic principles of the σ,π-approximation and the Hückel method are presented. Algorithms for calculating the energy and analytical form of the wave functions of π-conjugated molecules are described. The concept of aromaticity is analyzed from structural and energetic perspectives. The capabilities of the Hückel method for the theoretical description of the electronic structure and properties of π-conjugated molecules are discussed.
Four homonuclear lanthanide-based coordination polymers were synthesized under hydrothermal conditions and obtained as microcrystalline powders. The resulting compounds, with the general formula [Ln2(ip)3(H2O)2]·H2On (H2ip = isophthalic acid; Ln = Sm (Ia), Eu (Ib), Tb (Ic), Dy (Id)), are isostructural and exhibit extended polymeric architectures driven by the coordination versatility of the isophthalate ligands. Powder X-ray diffraction (PXRD) confirmed their phase purity and structural consistency, while Fourier-transform infrared spectroscopy (FTIR) evidenced the coordination through the carboxylate groups. Thermogravimetric analysis coupled with differential scanning calorimetry (TGA/DSC) revealed high thermal stability, with framework decomposition occurring only above 516°C. Photoluminescence investigations revealed characteristic lanthanide-centered visible emissions. The emission lifetimes were measured as 0.60699 ms for (Ia), 0.39287 ms for (Ib), 0.79544 ms for (Ic), and 0.69231 ms for (Id), and the quantum yields were also determined to evaluate their photophysical performance. CIE 1931 coordinates spanning orange (Sm3+: 0.34, 0.31), pink-red (Eu3+: 0.34, 0.27), green (Tb3+: 0.31, 0.52), to cyan (Dy3+: 0.35, 0.37), reflecting efficient ligand-to-metal energy transfer. These results highlight isophthalate ligands as versatile platforms for robust lanthanide coordination polymers with full-spectrum visible tunability, underscoring their potential for luminescent devices, optical sensors, and photonic materials.
This material presents current knowledge on the historical development of concepts concerning atomic structure. The modern quantum-theoretical view of the structure of one-electron particles is considered. The wave function of a hydrogen-like atom is discussed as a solution of the Schrödinger equation, and a chemical interpretation of the results obtained from this solution is provided. The meaning of quantum numbers and their relationship to the properties of the electron are explained.
The presented material contains general information on the structure of matter at the level from elementary particles to nuclei and constitutes part of the course “Structure of Matter.” The history of the discovery and the characteristics of elementary particles, the basic principles of the standard model of matter, and modern concepts of nuclear structure and radioactivity are consistently presented.
The molecular structures and relative energies of trans and cis isomers of low-spin bis(ligand) nickel complexes (with five-membered metallocycles) with o-hydroxy- and o-mercaptoanilines (coordination unit NiN2X2 (X = O, S)) are calculated by the density functional theory (DFT) method. The kinetic factor of structure formation for the NiL2 complexes is studied in terms of the stepwise model of the reaction mechanism of their formation (Ni++ + (L)– → (NiL)+, (NiL)+ + (L)– → NiL2). The trans isomer for the NiL2 complexes (X =O) and cis isomer for the NiL2 complexes (X = S) are preferred due to both an energy gain of one of possible configurations and also its kinetic accessibility combined with the balance of activation barriers for isomerization of the products formed in the first step of interaction of the initial reactants.
This article describes modern approaches to the description of the electronic structure of multielectron atoms. The problem of solving the Schrödinger equation for systems containing two or more electrons is discussed. Approaches to the approximate solution of the Schrödinger equation and the features of electron distribution among atomic orbitals in multielectron atoms are considered. The concept of an atomic term and methods for its determination are also discussed.
The heterobimetallic coordination polymer [FeMg2O(DTPA)]n·nH2O (I) (DTPA = diethylenetriaminepentaacetic acid) was synthesized under mild conditions and demonstrated dual functionality for degrading Methyl Orange as well as adsorbing Pb2+. The structure features three metal atoms with distinct coordination environments, including Fe(DTPA)2– units anchored to a magnesium chain framework. The observed catalytic activity suggests that the steric hindrance around the iron center as the catalytic active site may play a key role in modulating the degradation efficiency. For Pb2+ adsorption, the coordination polymer follows pseudo-second-order kinetics, indicating a chemisorption mechanism. Furthermore, the adsorption behavior is consistent with the Langmuir model, suggesting monolayer adsorption on a homogeneous surface. This study on the structure-property relationship of I offers valuable insights for the rational design of functional complexes, potentially inspiring new strategies for efficient wastewater treatment.
Modern concepts of chemical bonding from the perspective of quantum chemistry are presented. The fundamental principles, prospects for further development, and limitations of the valence bond and molecular orbital methods for describing the structure and properties of molecular species are discussed. Approaches to the construction of molecular wave functions and the corresponding changes in molecular energies are illustrated using specific examples of diatomic species.
