Structure Of HL Research Articles

Synthesis, characterization and crystal structures of nickel(II) and zinc(II) compounds derived from N,N’-bis(4-bromo-2-hydroxybenzylidene)-2-hydroxy-1,3-propanediamine

A new Schiff base compound N,N’-bis(4-bromo-2-hydroxybenzylidene)-2-hydroxy-1,3-propanediamine (H2L) has been prepared. With the Schiff base as ligands, two new nickel(II) compounds [NiL] (1) and [Ni3L2(CH3COO)2(CH3OH)2] (2), and two new zinc(II) compounds [ZnL(OH2)] (3) and [Zn3L2(CH3COO)2]·CH3OH·2dmf (4), were synthesized. The Schiff base and the four coordination compounds have been characterized by means of elemental analysis, IR and UV–Vis spectra, as well as 1H and 13C NMR spectra (for H2L). Structures of H2L and the coordination compounds were further determined by single crystal X-ray diffraction. The Ni atom in compound 1 is in square planar coordination, and those in compound 2 are in octahedral coordination. The Zn atom in compound 3 is in square pyramidal coordination. The outer and inner Zn atoms in compound 4 are in square pyramidal and octahedral coordination, respectively. The self-assembly of the coordination compounds is discussed.

Synthesis and Characterization of 4-amino-N'-[(1E)-1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)ethylidene]benzohydrazide and its Cu(II), Ni(II), Zn(II) and Mn(II) Complexes

New benzohydrazone compound, 4-amino-N'-[(1E)-1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)ethylidene] benzohydrazide (HL1) and its Cu(II), Ni(II), Zn(II) and Mn(II) complexes were synthesized. The structures of HL1 and its complexes were elucidated by elemental analysis and IR, UV-Vis, 1H and 13C NMR spectroscopy and mass spectrometry. The infrared spectral data of the complexes revealed that HL1 coordinated with the metal ions through azomethine nitrogen, enolic oxygen and amide carbonyl oxygen atoms, hence, HL1 behaves as a monobasic tridentate ligand. UV-Vis data revealed that Zn(II) and Mn(II) complexes adopted octahedral geometry, while Cu(II) and Ni(II) complexes had five-coordinate and square-planar geometries respectively. The mass spectra data and elemental analysis values are in accordance with the calculated values for the suggested molecular formula of the complexes, a confirmation of the 1:1 ligand to metal stoichiometry in case of Cu(II) complex and 2:1 ligands to metal stoichiometry in case of the other complexes.

Investigation on DNA/Protein interaction of thiosemicarbazone based octahedral nickel(II) and iron(III) complexes

2-acetylpyrzine N-(4)-cyclohexylthiosemicarbazide (H2L) and its metal complexes of Ni(II) and Fe(III) have been synthesized. The structure of H2L and corresponding metal complexes are proposed based on the elemental analysis, UV-Visible, FT-IR spectroscopy, and Far IR. It is evident by means of single diffraction X-ray crystallography that there is a distortion in the octahedral geometry owing to the two units of ligands surrounding the metal ion. To exploit the medicinal potential of the complex thus synthesized, their chemical interactions with Bovine Serum Albumin and CT-DNA were studied at normal physiological conditions using UV–Visible, fluorescence spectral, and viscosity measurement techniques. The results obtained from these studies revealed that the complexes exhibit high affinity for DNA with an affinity constant of 106 M−1 and show non-covalent intercalation. The binding constant (Ka) was calculated by using UV–Visible titration from which it is inferred that Ni(II) has more affinity toward CT-DNA compared to Fe(III) complex. Also, it is established by that there were no extrinsic agents responsible for the DNA cleavage by the complexes. Also, absorption and fluorescent techniques were incorporated to study the interactivity of NiL2 and FeL2 with bovine serum albumin (BSA). In-silico methods were adapted to evaluate the DNA-complex interactions. The outcome of experimental as well as in-silico studies suggests that the metal complexes intercalate with the CT-DNA molecules.

Study of the Synthesis and Application of a Fluorescence‐Enhanced Mg2+ Probe

AbstractA Schiff base fluorescent probe compound H2L (N′‐(4‐bromo‐2‐hydroxy‐benzylidene)‐3‐hydroxy‐2naphthohydrazide) was synthesized using 3‐hydroxy‐2‐naphthoic acid hydrazide as raw material. The structure of H2L was characterized by NMR, IR, MS, and XRD methods. The fluorescence performance of H2L was studied by UV and FS. The results show that in 1 : 4 water system /DMSO solution (water system: 20 % triethanolamine:0.1 mol/L L‐cysteamine acid=1 : 1), H2L can be used to quickly identify Mg2+ with an obvious fluorescence enhancement and redshift. A color change “light green→bright yellow” can be clearly observed with the naked eye. The Mg2+ concentration shows a good linear relationship in the range of 0–1.0×10−5 mol/L, with a detection limit of 1.77×10−7 mol/L with good stability and reversibility. The response mechanism was explored through Job's curve, NMR titration and MS, which showed that Mg2+ can form a 1 : 1 complex with H2L. A gel (SAL) was prepared by doping H2L into sodium alginate (SA). SAL was found to show good adsorption properties for Mg2+ and can be easily distinguished by the naked eye under ultraviolet light. The microscopic morphology and composition of SAL before and after Mg2+ adsorption were analyzed by SEM‐EDS. H2L can be used for the qualitative detection of Mg2+ in actual water samples without being affected by other common metal ions, and has potential application value in the field of environmental detection.

Synthesis and structural characterization of N‐methylanthraniloyl‐ (4‐ethylthiosemicarbazide) and its Cu(II) trinuclear complex

AbstractThe new ligand N‐methylanthraniloyl(4‐ethylthiosemicarbazide) H2L was synthesized by the treatment of anthranilic acid hydrazide and ethyl isothiocyanate in absolute ethanol. The composition and structure of H2L were characterized by spectroscopic methods such as ESI MS, IR, 1H and 13C{1H} NMR spectroscopy as well as SCXRD. Reaction of H2L and mixture of [Cu(MeCN)4](PF6) and o‐phenanthroline in methanol gave rise to a cationic Cu(II) trinuclear complex, which could be separated as PF6– salt with the composition of [Cu3(L)2(o‐phen)2](PF6)2. The spectroscopic and X‐ray crystallographic data analyses demonstrated that H2L deprotonates hydrazide protons and the resulting dianion {L2–} acts as bridging ligand of which most potential donor atoms form stable chelates with Cu(II) ions. In particular, the central Cu(II) ion coordinates with two dianions {L2–} via (O, N2) donor sets, thereby adopting a distorted square planar coordination mode with trans configuration. While each of two terminal Cu(II) ions is five‐coordinate with the coordination sphere composed of (S, N1, Namine) and (N,N) donor sets belonging {L2–} and o‐phenanthroline, respectively.

Nickel(II) complexes with N,O‐donor thiopseudourea ligands: Syntheses, structures, and catalytic applications in Kumada–Corriu cross‐coupling reactions

Synthesis, characterization, and physical properties of benzyl‐N′‐(4‐R‐benzoyl)‐N‐(2,6‐diisopropylphenyl)carbamimidothioates, HL1 (R = H) and HL2 (R = Cl), and their nickel(II) complexes having the general molecular formula [Ni(L1/2)2] (1 and 2) have been reported. Elemental analysis, magnetic susceptibility, solution electrical conductivity, and various spectroscopic (IR, UV–Vis, and 1H NMR) measurements were used to characterize HL1, HL2, and the two complexes (1 and 2). The molecular structures of all four compounds were determined by single‐crystal X‐ray crystallographic studies. The structures of HL1 and HL2 showed the imino‐ketone form of both compounds. In each of 1 and 2, the six‐membered chelate ring forming iminolate‐O and azomethine‐N donor two (L1/2)− ligands form a square‐planar trans‐N2O2 coordination environment around the metal center. The spectroscopic characteristics of HL1, HL2, 1, and 2 are consistent with their molecular structures. Both complexes were successfully employed as efficient catalysts in Kumada–Corriu CC cross‐coupling reactions of aryl bromides with phenylmagnesium bromide. The reactions provided biaryl products in good to excellent yields with a good substrate scope.

Salicylic aldehyde-n(4)-(4-ethoxyanilinyl) thiosemicarbazone: optimization of synthesis by surface response and structural characteristics

Salicylic aldehyde-N(4)-(4-ethoxyanilinyl)thiosemicarbazone (H2L) was synthesized by condensation between salicylic aldehyde (SA) and N(4)-(4-ethoxyanilinyl)thiosemicarbazide (TSCZ) in presence of glacial acetic acid as a homogeneous catalyst in ethanol. As a result of analysis by the surface response based on Box – Hunter model with the confidence level of 95%, the expectable yield reached the highest point (around 68%) at 80oC for 10 minutes when approximately 1 mole of SA reacted to equivalently 1 mole of TSCZ. The structure of H2L was solved by IR, UV-Vis, 1H and 13C NMR, HSQC, HMBC and HRMS, which indicated that the thioketone is the predominant form of H2L in the solid phase. The UV-Vis data in variety of pH showed that H2L was assigned to be a diacid with pKa1 = 8.8 and pKa2 = 13.6.

Coordination Compounds of Bivalent Metals with (Z)-4-(2-Hydroxy-5-nitrophenyl)hydrazono-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one: Crystal and Molecular Structure of C16H13N5O4

Five novel metal coordination compounds with (Z)-4-(2-hydroxy-5-nitrophenyl)hydrazono-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (H2L) have been prepared and isolated in crystalline state. Crystal and molecular structure of H2L have been established by X-ray diffraction study. A molecule of the organic compound exists in crystal state as a nearly flat hydrazo tautomer stabilized by intramolecular hydrogen bonds. Metal coordination is tridentate chelate, which has been confirmed by IR, electronic, 1H NMR, and EPR spectroscopy and DFT/B3LYP quantum chemical modeling. Coloristic and fungicidal properties of H2L and its metal complexes have been studied.

Inhibition studies of Jack bean urease with hydrazones and their copper(II) complexes

A series of copper(II) complexes, [CuCl2(HL1)]·CH3OH (1), [CuL2(ONO2)] (2), [CuBrL2] (3) and [CuL3(NCS)(CH3OH)] (4) were prepared from 3,5-dihydroxy-N′-(pyridin-2-ylmethylene)benzohydrazide (HL1), 2-hydroxy-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL2) and 4-methoxy-N′-(pyridin-2-ylmethylene)benzohydrazide (HL3). The compounds were characterized by physico-chemical methods. Structures of HL1 and the complexes were further confirmed by single crystal X-ray diffraction. The metal atoms in complexes 1 and 4 display square pyramidal coordination, in complexes 2 and 3 display square planar coordination. The inhibitory effects of the compounds on Jack bean urease were evaluated. The results showed that the hydrazone HL1 and complexes 1 and 4 have significant urease inhibitory activities, with IC50 values of 8.2 ± 1.5, 6.3 ± 1.7, and 3.1 ± 1.2 μmol·L−1, respectively. Complexes 2 and 3 show medium urease inhibitory activities, with IC50 values of 35.7 ± 3.1, and 41.5 ± 2.7 μmol·L−1, respectively. Molecular docking study of the compounds with Jack bean urease was performed to study the probable binding modes. The compounds with effective urease inhibitory activities anchor well in the active center of the urease and extend to the entrance of the binding pocket by interacting with its key amino acid residues. The results endorse that the hydrazone compound HL1 and complexes 1 and 4 may serve as structural templates for the design and development of novel urease inhibitors.

Nano‐synthesis and spectral, thermal, modeling, quantitative structure–activity relationship and docking studies of novel bioactive homo‐binuclear metal complexes derived from thiazole drug for therapeutic applications

Seven novel homo‐binuclear Cr(III), Fe(III), Cu(II), ZrO(II), Sn(II), Pb(II) and Ce(III) nanosized complexes of a thiazole drug (H2L) were synthesized for chemotherapeutic applications. H2L was prepared via a condensation reaction between 2‐(4‐aminobenzenesulfonamido)thiazole and 2‐hydroxybenzaldehyde. The structures of H2L and its metal complexes were investigated by various means. These included microanalysis, 1H NMR, 13C NMR, Fourier transform infrared, UV–visible, electron spin resonance and mass spectroscopies, transmission electron microscopy (TEM), powder X‐ray diffraction (XRD), thermogravimetric analysis (TGA) and molar conductivity. The measurements revealed that H2L coordinates with the metal ions through two chelating centers, indicating its behavior as a dibasic tetradentate ligand. The first center involves the nitrogen of azomethine (CH═N) and the α‐hydroxyl oxygen while the other center is the thiazole nitrogen and the sulfonamide oxygen. From spectroscopic and analytical data, the Cr(III), Fe(III) and Ce(III) complexes have octahedral geometries, whereas the Cu(II), ZrO(II), Sn(II) and Pb(II) complexes have tetrahedral geometries. TEM and XRD measurements unambiguously showed the nanometric particle sizes of the complexes. The activation thermo‐kinetic parameters, E*, ∆H*, ∆S* and ∆G*, of the various decomposition steps of the complexes were determined mathematically from the TGA curves. Gaussian09 and quantitative structure–activity relationship modeling studies were utilized to verify the biological and structural feature relationships. Docking studies were performed to throw more light on the biological priority of the proposed drugs, using microorganism protein receptors. The antitumor and antimicrobial efficiencies of the H2L drug and its complexes were determined to estimate their potential therapeutic utility. In general, the complexes showed greater antitumor and antimicrobial efficiencies than the H2L drug. The Fe(III) complex exhibited efficient antimicrobial activities against Candida albicans and Staphylococcus aureus and its efficiency is equivalent to that of standard drugs. The Cu(II) complex showed the greatest cytotoxic activity towards HEPG2.

Synthesis, structural characterization and biological evaluation of mononuclear transition metal complexes of zwitterionic dehydroacetic acidN‐aroylhydrazone ligand

Synthesis and characterization of mononuclear transition metal complexes viz., Co(II), Ni(II), Cu(II) and Zn(II) with a newly designed ligand, (E)‐2‐benzamido‐N'‐(1‐(2‐hydroxy‐6‐methyl‐4‐oxo‐4H‐pyran‐3‐yl) ethylidene) benzohydrazide (H2L) are reported. Molecular structures ofH2L, Ni(II) and Cu(II) complexes were determined by single‐crystal X‐ray diffraction studies. The structures were stabilized by various intra/inter‐molecular H‐bonding, C‐H···π and π···π stacking interactions.H2Lexists in zwitterionic form and acts in a monoanionic manner. Ligand/metal ratio was 2:1 for cobalt, nickel and zinc, whereas 1:1 for the copper complex. Co(II), Ni(II) and Zn(II) complexes display distorted octahedral geometry, while the Cu(II) complex shows distorted square pyramidal geometry around the metal ion. Hirshfeld surface analysis and 2D fingerprint plots revealed thatH2Land its complexes were supported mainly by H⋯H, O⋯H and C⋯H intermolecular interactions. The synthesized compounds were screened forin vitroanti‐inflammatory activity by gelatin zymography and the activity was comparable with tetracycline. Their cleavage behavior towards calf thymus DNA has been studied using agarose gel electrophoresis method.H2Land Cu(II) complex were selected by National Cancer Institute (NCI) forin vitrosingle dose testing in the full NCI 60 cell lines panel assay. Finally, molecular docking simulation effectively proves the binding of all the synthesized compounds at cyclooxygenase‐2 (COX‐2) active sites.

4-Fluoro-N'-(2-hydroxy-3-methoxybenzylidene) benzohydrazide and its Oxidovanadium(V) Complex: Syntheses, Crystal Structures and Insulin-enhancing Activity.

A hydrated hydrazone compound, 4-fluoro-N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide monohydrate (H2L · H2O), was prepared and characterized by elemental analysis, HRMS, IR, UV-Vis and 1H NMR spectroscopy. Reaction of H2L, kojic acid (5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one; Hka) and VO(acac)2 in methanol afforded a novel oxidovanadium(V) complex, [VO(ka)L]. The complex was characterized by elemental analysis, IR, UV-Vis and 1H NMR spectroscopy. Thermal analysis was also performed. Structures of H2L and the complex were further confirmed by single crystal structural X-ray diffraction. The vanadium complex is the first structurally characterized vanadium complex of kojic acid. Insulin-mimetic tests on C2C12 muscle cells indicate that the complex significantly stimulated cell glucose utilization with cytotoxicity at 0.11 g L-1.

Synthesis, structural, and spectral studies of diorganotin(IV) complexes with 2–hydroxy-5-methylbenzaldehyde-N(4)-cyclohexylthiosemicarbazone

AbstractThree new diorganotin(IV) complexes, [Me2Sn(L)] (2), [Bu2Sn(L)] (3), and [Ph2Sn(L)] (4) [where H2L (1) = 2-hydroxy-5-methylbenzaldehyde-N(4)-cyclohexylthiosemicarbazone] have been synthesized by reacting the corresponding diorganotin(IV) dichloride with H2L (1) in absolute methanol in the presence of potassium hydroxide. All the compounds have been characterized by CHN analyses, UV–vis, FT-IR, 1H, 13C, and 119Sn NMR spectroscopy. The molecular structures of H2L (1) and 2 have been confirmed by single crystal X-ray diffraction analysis. H2L (1) is found to be in the thiol tautomeric form. The X-ray structure of 2 showed that H2L is a tridentate ligand and binds to the tin(IV) atom via the phenolic oxygen, azomethine nitrogen, and thiolate sulfur. Complex 2 has a triclinic structure and the coordination geometry of tin(IV) is distorted trigonal bipyramidal. The sulfur and oxygen are in axial positions while the azomethine nitrogen of 1 and two methyl groups occupy the equatorial positions. The C-Sn-...

Synthesis, Characterization, and Hydrolytic Behavior of Diorganotin(IV) Coordination Polymers with Layered Structural Motifs

The synthesis and structural characterization of the layered diorganotin coordination polymers nBu2Sn(HL)(OSO2Me) (1) and nBu2Sn(HL1)(OSO2Me) (2) derived from the silaalkylphosphonic acids RR12Si(CH2)3P(O)(OH)2 [R = Ph, R1 = Me (H2L); R = R1 = Et (H2L1)] are presented. The structure of H2L exhibits O-H···O hydrogen bonding and π-π interactions to form a unique three-dimensional supramolecular assembly in the solid state. The asymmetric units of 1 and 2 are composed of centrosymmetric eight-membered [-Sn-O-P-O-]2 cyclic rings with appended sulfonate groups, which provide layered connectivity to the structures. For 1, the presence of C-H···π interactions between the dangling phenyl rings of the silaalkyl chains favors a lamellar arrangement with an interlayer spacing of 16.9 A. Upon exposure to humid conditions, these polymers undergo slow transformation to nBu2Sn[O3P(CH2)3SiRR12] with the elimination of methanesulfonic acid.

Synthesis, structure, and spectral studies of zinc and cadmium complexes with 2-tosylaminobenzaldehyde and aminoquinoline azomethine derivatives

New zinc and cadmium complexes with 3-[2-(N-tosylaminobenzylidene)]aminoquinoline (HL1) and 6-[2-(N-tosylaminobenzylidene)]aminoquinoline (HL2) were synthesized. The structures of HL1, HL2 and complexes ML2 (M = Zn, Cd) were established based on the elemental analysis data, IR spectroscopy, 1H NMR spectroscopy, and quantum chemical calculations. Electron absorption and photoluminescence spectra of the complexes were studied. OLED devices were developed, where ZnL22 complexes were used as an emission layer. This device emitted yellow light with CIE x = 0.436, y = 0.492 and x = 0.463, y = 0.484, maximum luminance at 10 V was 126 and 150 cd m−2, respectively.

New 1,2,4-triazole-based azo–azomethine dye. Part III: Synthesis, characterization, thermal property, spectrophotometric and computational studies

A new 1,2,4-triazole-based azo–azomethine compound, H2L, has been prepared by condensation reaction of 1-(3-formyl-4-hydroxyphenylazo)-4-ethylbenzene with prepared triazole-based diamine. The structure of H2L was characterized by using FT-IR, UV–Vis and 1H NMR spectroscopic methods as well as elemental analysis. Hard model chemometrics method has been used to determine the formation constants of zinc(II), copper(II), nickel(II) and cobalt(II) complexes of H2L in DMSO by UV–Vis spectrophotometric method. Solvatochromic behavior of the dye has been also investigated in some organic solvents with different polarities. Thermal properties of the prepared dye was examined by thermogravimetric analysis. Results indicated that the framework of the dye was stable up to 245°C. Furthermore,1H chemical shifts and UV–Vis of H2L were studied by the gauge independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and time-dependent density functional theory (TD-DFT) methods respectively at the level of density functional theory using B3LYP/6-311+G(d) basis sets in DMSO. The computational data are in reasonably good agreement with the experimental data.

Synthesis and X-ray crystal structures of N′-(2-hydroxy-5-methoxybenzylidene)-4-dimethylaminobenzohydra zide and its oxovanadium(V) complex with catalytic property

A new benzohydrazone compound N′-(2-hydroxy-5-methoxybenzylidene)-4-dimethylaminobenzohydrazide (H2L) and its oxovanadium(V) complex [VOL(BHA)] · H2O, where HBHA is benzohydroxamic acid, were prepared and structurally characterized by physic-chemical methods and single crystal X-ray diffraction. The benzohydrazone compound crystallizes in the monoclinic space group C2/c with a = 35.5873(12), b = 10.4628(4), c = 18.6059(6) A, β = 109.499(1)°, V = 6530.4(4) A3, Z = 16, R1 = 0.0603, and wR2 = 0.1575. The oxovanadium(V) complex crystallizes in the triclinic space group \(P\bar 1\) with a = 7.4775(4), b = 9.7837(5), c = 17.7076(8) A, α = 99.457(2)°, β = 98.699(2)°, γ = 101.429(2)°, V = 1229.7(1) A3, Z = 2, R1 = 0.0431, and wR2 = 0.0937. X-ray structural analysis indicates that the benzohydrazone ligand L2-coordinates to the V atom through the phenolate O, imino N, and enolic O atoms. The V atom in complex I is coordinated by one benzohydrazone ligand and one BHA ligand, as well as one oxo O atom, forming an octahedral coordination. The crystal structures of H2L and I are stabilized by hydrogen bonds. Complex I is an effective catalyst for sulfoxidation.

Coordination compounds of some d metals with nitrophenylhydrazone oxopyridine (pyrimidine) derivatives: Crystal and molecular structure of C10H9N5O6

Twelve new d-metal complexes with 5-[(4-nitrophenyl)hydrazo]pyrimidine-2,4,6-trione (HL1) and 4-methyl-5-[4-nitrophenylhydrazo]-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitryl (HL2) have been synthesized and separated out in the crystalline state. The crystal and molecular structures of HL1 have been solved by X-ray diffraction analysis. The organic molecule exists in the crystalline state as a planar hydrazo tautomer stabilized by intramolecular hydrogen bonds. Metal coordination is bidentate chelate. The acid-base equilibria and complexation of the ligands in solutions have been studied, and the complexation constants have been found.

Syntheses, spectroscopy, and X-ray structures of 3-{(R)-(Ar)-ethylimino}-1,3-dihydro-indol-2-one (Ar = Ph, MeOC6H4, BrC6H4, 1-naphthyl) and [Rh(η4-cod){3-((R)-(Ar)-ethylimino)-3H-indol-2-olato}

Condensation of 1H-indole-2,3-dione (isatin) with (R)-(Ar)-ethylamines gives enantiopure Schiff bases, 3-{(R)-(Ar)-ethylimino}-1,3-dihydro-indol-2-one (HL) {Ar = Ph (HL1), 2-MeOC6H4 (HL2), 4-MeOC6H4 (HL3), 4-BrC6H4 (HL4), and 1-naphthyl (HL5)}. The Schiff bases readily coordinate to [Rh(μ-O2CMe)(η4-cod)]2 (cod = 1,5-cyclooctadiene) to give mononuclear [Rh(η4-cod){3-((R)-(Ar)-ethylimino)-3H-indol-2-olato}] {Ar = Ph (1), 4-MeOC6H4 (2), and 4-BrC6H4 (3)}, respectively. The Schiff bases and complexes have been fully characterized by IR, UV-Vis, 1H-NMR, mass, and circular dichroism (CD) spectrometry. Polarimetry and CD measurements show the enantiopurity of the Schiff bases as well as the complexes. 1H NMR measurements reveal slow conversion of the lactam to the enol form of the Schiff bases in solution. In the solid state the lactam form dominates as shown by crystal structures of HL1 and HL4. While gross structural features of both are similar, the molecules differ significantly in the relative orientations of the aryl and lactam rings. The difference is mostly rotation about the N2–C9 bond with different C8–N2–C9–C11 torsion angle of +89.77(12)° for HL1 and C2–N2–C9–C11 of +106.8(3)° for HL4.

Syntheses and structures of p-HOOCC6F4COOH · H2O (H2L · H2O) and luminescent coordination polymers [Tb2(H2O)4(L)3 · 2H2O] n and Tb2(Phen)2(L)3 · 2H2O

Compounds p-HOOCC6F4COOH · H2O (H2L · H2O), [Tb2(H2O)4(L)3 · 2H2O] n (I), and Tb2(Phen)2(L)3 · 2H2O (II) are synthesized. According to the X-ray structure analysis data, the crystal structure of H2L · H2O is built of centrosymmetric molecules H2L and molecules of water of crystallization. The crystal structure of compound I is built of layers of coordination 2D polymer [Tb2(H2O)4(L)3] n and molecules of water of crystallization. The ligands are the L2− anions performing both the tetradentate bridging and pentadentate bridging-chelating functions. The coordination polyhedron TbO9 is a distorted three-capped trigonal prism. Acid H2L manifests photoluminescence in the UV region (λmax = 368 nm). Compounds I and II have the green luminescence characteristic of the Tb3+ ions, and the band with λmax = 545 nm (transition 5 D 4→ 7 F 5) is maximum in intensity. The photoluminescence intensity of compound II is higher than that for compound I.