Effect of solvent on the crystal structures of copper(II) complexes based on 4′-(4-methoxyphenyl)-2,2′:6′,2″-terpyridine and 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine

Four homoleptic copper(II) complexes, [Cu(Meophtpy)₂](ClO₄)₂ (Meophtpy = 4′-(4-methoxylphenyl)- 2,2′:6′,2″-terpyridine) (I), [Cu(Meophtpy)₂](ClO₄)₂ · 2H₂O (II), [Cu₂(m-Clphtpy)₄](ClO₄)₄ (m-ClPhtpy = 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine) (III), and [Cu₂(m-ClPhtpy)₄](ClO₄)₄ (IV) have been synthesized by hydrothermal methods and characterized by IR, elemental analysis and single crystal X-ray diffraction (CIF files CCDC nos. 963375 (I), 885457 (II), 963377 (III), and 963376 (IV)). Complex II is a polymorph of I and complex IV is a polymorph of III. All these complexes are obtained with 95% ethanol solution or 50% ethanol solution and the solvent control on the crystallization are obviously found. In all complexes, the face-to-face interactions between pyridyl rings or phenyl rings facilitate the construction of 3D network in the crystal in addition to hydrogen bonds. The fluorescence properties of these complexes have been investigated.     

Spectroscopic, thermal and structural studies of a new mercury(II) complex of 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine (pyterpy) ligand, [Hg (hpyterpy)(SCN)2]2(MeSO4)2

A new mercury(II) complex [Hg(Hpyterpy)(SCN)₂]₂(MeSO₄)₂ was prepared from the reaction of 4′-(4-pyridyl)-2,2′:6′,2″- terpyridine (pyterpy), as a polypyridyl ligand, with mercury(II) thiocyanate. The compound was characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy and its structure was determined by X-ray single-crystal diffraction. The thermal stability of compound was studied by thermogravimetric (TG) and differential thermal analyses (DTA).     

Synthesis and characterization of mono- and binuclear copper(II) complexes with 2,2′:6′,2″-terpyridine (terpy) and carboxylates: X-ray crystal structure of [Cu(terpy)(OOCH)(OH2)](ClO4) complex

Perchlorate and hexafluorophosphate salts of monomeric [Cu(terpy)(OOCH)(OH₂)]⁺ and dimeric [Cu(terpy)(OOCR)]₂²⁺ cations (terpy = 2,2′:6′,2″-terpyridine, R = CH₃ or C₂H₅) have been synthesized and characterized by IR, electronic and ESR spectra, and analytical data. Spectroscopic results indicate a five-coordinate, close-to-square pyramidal geometry around the copper(II) ion. The half-field absorption in the ΔM_s = 2 region of powdered X-band ESR spectra has been observed for the dimeric species. The crystal structure of [Cu(terpy)(OOCH)(OH₂)](ClO₄) has been determined by X-ray diffraction methods. The compound crystallizes in the space group P2₁/c with unit-cell dimensions: a = 7.341(3), b = 13.919(2), c = 18.081(3) Å, β = 101.68(3)°, V = 1809(1) ų, Z = 4. The structure was refined to R = 0.044, R_w = 0.051.     

Syntheses and characterization of two 1D Cu(II) coordination polymers with 2,2′:6′,2″-terpyridine ligand

The solution reactions of CuCl₂ with 2,2′:6′,2″-terpyridine (Terpy) and dicarboxylic acid (glutaric acid or suberic acid) afforded two 1D coordination polymers [Cu(Terpy)(C₅H₆O₄)] _n (I) and [Cu(Terpy)(C₈H₁₂O₄)] · 3H₂O (II) and their structures were characterized by IR, TG-DTA, and single-crystal X-ray diffraction. Crystallographic data for I: C₂₀H₁₆CuN₃O₄, M _r = 425.90, monoclinic, space group C2/c, a = 10.335(2), b = 21.193(4), c = 8.580(2) Å, β = 111.99(3)°, V = 1742.5(6) ų, Z = 4, ρ _c = 1.623 g/cm³, F(000) = 872, R = 0.0304 and wR = 0.0915; and those for II: C₂₃H₂₉CuN₃O₇, M _r = 523.03, triclinic, space group P \(\bar 1\), a = 8.362(2), b = 10.605(2), c = 14.617(3) Å, α = 73.26(3)°, β = 86.23(3)°, γ = 69.45(3)°, V = 1161.3(4) ų, Z = 2, ρ _c = 1.496 g/cm³, F(000) = 546, R = 0.0636 and wR = 0.1106. X-ray diffracion studies reveal that both complexes I and II feature 1D chain. The 1D polymer chains are connected by π-π-stacking interactions to generate 2D supramolecular layers.     

4′-(2-Methylphenyl)-2,2′:6′,2″-terpyridine: coordination chemistry with Ni(II), Cu(II), Zn(II) and Ag(I)

The synthesis of 4′-(2-methylphenyl)-2,2′:6′,2″-terpyridine (L) has been improved. The coordination chemistry of the ligand was explored using Ni(II), Cu(II), Zn(II), and Ag(I) ions. X-ray crystallography, elemental analysis, NMR, and mass spectrometry were used to characterize the 13 new compounds that have been synthesized. Under different reaction conditions, Ni(II), Cu(II), and Zn(II) produced discrete complexes, sometimes containing more than one metal ion, while Ag(I) furnished a polymeric spiral complex in which the central pyridine nitrogen of each terpyridine ligand bridges two Ag(I) ions. Crystallographically characterized complexes are [Ni(L)₂]Cl₂, [Ni₂Cl₄(L)₂], [Ni(L)(OH₂)₃]Cl₂, [Ni(L)₂]Br₂, [Cu(L)(OH₂)(OSO₃)], [Cu₃Cl₆(L)₂], [Cu(L)(OH)(OH₂)₂]PF₆, [Cu(L)₂](OTf)₂, [Cu(L)(OAc)₂], [Zn(L)(OAc)₂], [Zn(L)Cl₂], [Zn(L)₂](NO₃)₂, [{Ag₂(μ-L)₂(μ-NO₃)}_n](NO₃)_n.     

Synthesis of 4′-(4‴-benzo-15-crown-5)-methyloxy-2,2′:6′,2″-terpyridine (L) and the crystal structure of its complexes with cobalt(II) and zinc(II): [ML2](ClO4)2 · 3H2O

The synthesis of 4′-(4?-benzo-15-crown-5)-methyloxy-2,2′:6′,2″-terpyridine (L) and is complexes with cobalt(II) and zinc(II) [CoL₂](ClO₄)₂ · 3H₂O (I) and [ZnL₂](ClO₄)₂ · 3H₂O (II) was described. For L and its complexes, the parameters of electronic absorption spectra in acetonitrile were determined and ¹H NMR signals were assigned. The structures of I and II were determined by X-ray crystallography. Compounds I and II are isostructural and consist of complex cations [ML₂]²⁺ (M = Co, Zn), ClO ₄ ^? anions, and crystal water molecules. The M atoms are located in special positions on twofold axes. The M atoms are surrounded by six N atoms of the terpyridine moieties of two organic molecular ligands. The M-N distance for the N(2) atoms of the central rings of the terpyridine moieties in both structures is shorter than for the side rings. The coordination polyhedra of the M atoms can be described as severely distorted octahedra. The major distortion of the octahedra is that the N…N distances in a terpyridine moiety are considerably shorter than those between the atoms of different moieties. The maximal deviation of the terpyridine atoms from the mean-square planes through these atoms is observed for the C(2) atom: 0.103(3) and 0.106(4) Å in I and II, respectively. The Co(1) and Zn(1) atoms are at a distance of, respectively, 0.1682(14) and 0.1415(17) Å from the corresponding planes.     

Photophysical Properties of 4′-(p-aminophenyl)-2,2′:6′,2′′-terpyridine

Spectral and photophysical investigations of 4′-(p-aminophenyl)-2,2′:6′,2′′-terpyridine (APT) have been performed in various solvents with different polarity and hydrogen-bonding ability.The emission spectra of APT are found to exhibit dual fluorescence in polar solvents, which attributes to the local excited and intramolecular charge transfer states, respectively. The two-state model is proven out for APT in polar solvent by the time-correlated single photon counting emission decay measurement. Interestingly, the linear relationships of different emission maxima and solvent polarity parameter are found for APT in protic and aprotic solvents, because of the hydrogen bond formation between APT and alcohols at the amino nitrogen N25. Furthermore, the effects of the complexation of the metal ion with tpy group of APT and the hydrogen bond formation between APT with methanol at the terpyridinenitrogen N4—N8—N14 are also presented. The appearance of new long-wave absorption and fluorescence bands indicates that a new ground state of the complexes is formed.     

Synthesis and spectroscopic characterization of new heteroleptic ruthenium(II) complexes incorporating 2-(2′-pyridyl)quinoxaline and 4-carboxy-2-(2′-pyridyl)quinoline

Starting from cis-[Ru(dcbpyH₂)₂Cl₂] (1), two new heteroleptic ruthenium(II) complexes, [Ru(dcbpyH₂)₂(L¹)](NO₃)₂ (L^1?=?2-(2′-pyridyl)quinoxaline (2), and [Ru(dcbpyH₂)₂(L²)](NO₃)₂ (L^2?=?4-carboxy-2-(2′-pyridyl)quinoline (4); dcbpyH_2?=?2,2′-bipyridine-4,4′-dicarboxylic acid), were synthesized and spectroscopically characterized. During the preparation of 2 and 4, the homoleptic [Ru(dcbpyH₂)₃]Cl₂ complex (3) was isolated as a side product. Characterization includes IR and Raman spectroscopy, UV-Vis, multinuclear NMR spectroscopy, elemental, and ESI-mass spectrometric analyses.     

Nickel(II), cobalt(II), copper(II), and zinc(II) complexes with 4′-(4‴-benzo-15-crown-5)methyloxy-2,2′:6′,2″-terpyridine: Syntheses and vibrational spectra

Complexes of 4′-(4′″-benzo-15-crown-5)methyloxy-2,2′:6′,2″-terpyridine (L) with metal perchlorates and hexafluorophosphates, [ML₂](ClO₄)₂ · nH₂O and [ML₂](PF₆)₂ · nH₂O · mC₂H₅OH (M = Ni(II), Co(II), Zn(II), Cu(II); n = 0–3; m = 0–2), were synthesized. Their vibrational spectra were studied. The spectral criteria for ligand coordination through the terpyridinic nitrogen atoms were established. The conformational structure of the B15C5 macrocycles of a ligand molecule in the synthesized complexes was proposed. The complexes were studied by thermogravimetry.     

Synthesis,vibrational spectra,and structure of 4′-(4″-benzo-15-crown-5)oxy-2,2′:6′,2″-terpyridine (L) and its transition metal complexes. Extraction and ion-selective properties of L

Complexes of Co(II), Ni(II), Zn(II), and Cu(II) perchlorates and hexafluorophosphates with 4′-(4″-benzo-15-crown-5)oxy-2,2′:6′,2″-terpyridine (L) [M(L)₂](ClO₄)₂ · 3H₂O and [M(L)₂](PF₆)₂ · 2H₂O were synthesized. The spectral criteria of ligand coordination through the terpyridine nitrogen atoms were established. An assumption concerning the benzo-15-crown-5 conformation in the ligand molecule in the synthesized complexes was made. The extraction and ion-selective properties of L were studied.     

Syntheses and characterization of three mercury(II) complexes, [Hg(phen)2(SCN)2], [Hg(2,2′-bipy)2(SCN)2] and [Hg(phen)2(NO3)2], thermal and fluorescence studies

Mercury(II) complexes of 1,10-phenanthroline (phen) and 2,2′-bipyridine (bipy), [Hg(phen)₂(SCN)₂] (1), [Hg(2,2′-bipy)₂(SCN)₂] (2) and [Hg(phen)₂(NO₃)₂] (3) have been synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy. The thermal stability of 1–3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The structure of 1 has been confirmed by X-ray crystallography. The complex is a monomer and the Hg atom has an unsymmetrical six-coordinate geometry, formed by four nitrogen atoms of the two phen ligands and two sulfur atoms of the two thiocyanate anions. Solid-state luminescent spectra of phen, 2,2′-bipy and 1–3 indicate emission with the maximum intensity at ca 467 nm upon excitation at 295 nm.     

Synthesis,characterization and in vitro antitumor behavior of a vanadium(V) complex with 4′-(3-methoxyphenyl)-2,2′:6′2″-terpyridine

A dioxovanadium(V) complex, [VO₂(moptpy)](ClO₄) (1, moptpy = 4′-(3-methoxyphenyl)2,2′:6′2″-terpyridine), was synthesized and characterized by elemental analysis, ESI-MS, UV–vis, IR, and ¹H, ¹³C, and ⁵¹V NMR. The cytotoxicity in vitro of 1 was evaluated against cancer cell lines HepG-2 (hepatocellular carcinoma), SGC-7901 (gastric carcinoma), SiHa (cervical cancer), BEL-7402 (hepatocellular), and rat PC-12 (pheochromocytoma) by the MTT method. The results demonstrated that 1 exhibits superior anticancer activity in vitro with much lower values of 50% inhibitive concentration (IC₅₀) against the selected cell lines than cisplatin, and 1 shows the highest cytotoxic activity toward SGC-7901 cells (IC₅₀ = 1.3 ± 0.1 μM) among the selected cell lines. A series of cellular morphological and staining experiments were carried out, and the results indicated that 1 can effectively induce apoptosis of SGC-7901 cells through a ROS-mediated mitochondrial dysfunction pathway. In addition, cellular incorporation and cell cycle analysis were also performed, and it was concluded from the experimental observations that 1 can efficiently enter into the cell nuclei, and the complex inhibits cell growth in SGC-7901 cell at G0/G1 phase.     

Synthesis,spectroscopy, thermal behavior,and X-ray crystal structure of two lead(II) complexes with 4′-(4-tolyl)-2,2′;6′,2″-terpyridine (ttpy)

Two new lead(II) complexes with 4′-(4-tolyl)-2,2′;6′,2″-terpyridine (ttpy), [Pb(ttpy)(µ-AcO)]₂(PF₆)₂ (1) and [Pb(ttpy)(µ-AcO)I]₂ (2), have been synthesized and characterized by CHN elemental analysis, ¹H NMR, ¹³C NMR, IR spectroscopy, and structurally analyzed by X-ray single-crystal diffraction. The thermal stability of these compounds has been studied by thermal gravimetric analysis and differential thermal analysis. Single crystal X-ray analysis shows that 1 and 2 are dimeric units with Pb–(µ-AcO)₂–Pb-type bridging, and the coordination number in 1 is six and in 2 is seven. The arrangement of donors suggests a gap in the coordination geometry around lead, possibly occupied by stereo-active lone pair of electrons on lead(II), so the coordination sphere is hemidirected. Furthermore, dimeric units are connected by a network of hydrogen bonds and π–π stacking as well. Electrochemical properties of free ligand and complexes have been investigated in the presence of tetrabutyl ammonium perchlorate as supporting electrolyte and by using a glassy carbon electrode. Both lead complexes show irreversible Pb(II) oxidation. Cyclic voltammetry indicates that these processes are diffusion-controlled. The data from electrochemical studies show that the total limiting current of each of the studied complexes corresponds to two-electron transfer.     

Synthesis of a new 2,2′：6′,2″-terpyridine derivative and its coordination property

A novel compound, （E）-4′-（4-（but-1-en-3-ynyl）phenyl）-2,2′：6′,2″-terpyridine 1 was synthesized from 4′-（4-bromomethylphenyl）-2,2P：6P,2PP-terpyridine phosphonium salt 2 and propargylaldehyde via Wittig reaction, and characterized by EI-MS and ^1H NMR as well as elemental analysis. The spectral changes of the compound in the presence of transition metal ions, such as Cu（I） or Zn（ID, are investigated.     

Cadmium(II) complexes of 4′-tolyl-2,2′:6′,2′′-terpyridine: synthesis,structures, and antibacterial activities

A straightforward synthetic method has been developed to prepare cadmium(II) complexes of 4′-tolyl-2,2′:6′,2″-terpyridine (ttpy) in good yields. These complexes are formulated as {[Cd(ttpy)(NO₃)₂][Cd₂(ttpy)₂(NO₃)₄]} (1), [Cd₂(ttpy)₂(N₃)₄]0.5CH₃OH?·?0.125H₂O (2), and {[Cd(ttpy)(SCN)(CH₃COO)][Cd(ttpy)(SCN)₂]₂} (3). Intermolecular, intramolecular, hydrogen bonding and π–π stacking interactions were observed in the complexes, and are responsible for the arrangement of complexes in the crystal packing and play essential roles in forming different frameworks of 1–3. The antibacterial activities of the synthesized complexes were tested against three gram positive bacteria and three gram negative bacteria.     

New cobalt and iron pivalate complexes with 2,2′:6′,2″-terpyridine: synthesis, structure, and magnetic properties

The mononuclear complexes (η³-terpy)M(Piv)²·MeCN (M = Fe ⁱⁱ (3) and Co ⁱⁱ (4), and Piv is the pivalate anion) were synthesized by the reactions of polymeric iron(ii) and cobalt(ii) pivalates with 2,2′:6′,2″-terpyridine (terpy). The oxidation of compound 3 affords the pentanuclear heterospin iron(ii,iii) complex (η³-terpy)Fe₅(μ₄-O)(μ₃-OH)(μ-OH)₂(μ-Piv)₇(η¹-Piv)₂ (5). All compounds were characterized by X-ray diffraction. Dedicated to the 90th anniversary of the L. Ya. Karpov Institute of Physical Chemistry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1186–1190, June, 2008.     

[Bis(trispivalatodimolybdenum (II))-μ-bis(4′-carboxylato-2,2′:6′,2″-terpyridine) ruthenium (II)] (2+) Tetrafluoroborate: Photophysical Studies

The photophysical properties of the title compound have been studied by fs and ns transient absorption spectroscopy. The electronic absorption spectrum consists of three principle absorptions assigned to terpy ¹LLCT at ~300 nm, ruthenium (II) t_2g⁶ to terpy ¹MLCT at ~470 nm and Mo₂ δ to terpycarboxylate at ~670 nm. The compound shows weak room temperature emission in THF solution at ~1,100 nm when excited into each of the aforementioned bands. This emission is assigned to the T₁ state, ³MMδδ*. Transient absorption spectroscopy indicates a lifetime for T₁ of 9.6 μs. This paper is dedicated to Prof. C. N. R. Rao.     

Hydrogen bonded networks based on Ni(II)-tetraazamacrocycle (tet-b) complexes: synthesis,isolation and structural characterization of α -[Ni(tet-b)(Cl)](ClO4) and α -[Ni(tet-b)(en)](ClO4)2

Five- and six-coordinate, α-[Ni(tet-b)(Cl)](ClO₄) (1) and α-[Ni(tet-b)(en)](ClO₄)₂ (2) (tet-b?= C-racemic-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) complexes have been synthesized and isolated from the reactions of α-[Ni(tet-b)](ClO₄)₂, which has trans-V (1R,4R,8R,11R,7S,14S or 1S,4S,8S,11S,7R,14R) conformation, with t-Bu₄NCl and ethylenediamine (en), respectively. The complexes have been characterized by X-ray crystallography. The crystal structure of 1 shows a distorted trigonal bipyramidal (TBP) coordination geometry composed of four nitrogen atoms from tet-b and a chloro group with an N₄Cl chromophore about the nickel(II) ion. The complex cations of 1 are assembled by the perchlorate ions via N–H?···?O hydrogen bonding to form 1-D zigzag chains along the [001] direction. The chains are linked through intermolecular hydrogen bonding where the coordinated chloro group of the complex cation forms two-center double hydrogen bonds with the adjacent N–H groups of the macrocyclic ligand along the [100] direction, resulting in a two-dimensional α-network. The crystal structure of 2 shows a distorted octahedral coordination environment consisting of four nitrogen atoms from tet-b and two from en with an N₆ chromophore about nickel(II) ion. The crystal packing analysis shows that the complex cations, α-[Ni(tet-b)(en)]²⁺ are interconnected by perchlorate ions through conventional two-center (N)H?···?O, and bifurcated (N)H?···?O?···?H(N) hydrogen bonding.