Single-crystal X-ray Structure Research Articles

Synthesis, crystal structure and DFT study of (3-(pyrrolidin-1-yl)-5-(trifluoromethyl)phenyl)boronic acid

Phenylboronic acid is a well-known bioactive molecule with a wide range of pharmacological properties. In this paper, (3-(pyrrolidine-1-yl)-5-(trifluoromethyl)phenyl) boric acid was synthesized by two steps. Its structure was characterized by IR, 1H NMR, 13C NMR and MS, its structure was confirmed by X-ray diffraction, and its crystallography and conformation were analyzed. DFT further analyzed its structure. The results show that the optimized DFT structure is consistent with the X-ray single crystal structure. The molecular electrostatic potential and frontier molecular orbital were further studied to provide reference for studying its physical and chemical properties.

Luminescent materials based on N-(3-nitrophenyl)-N'-(4-R-C6H4)oxamato zincate(II) complexes

A series of N-(3-NO2C6H4)-N'-(4-R-C6H4)oxamato zincate(II) complexes (3a, R = OMe; 3b, R = Me; 3c, R=H; 3d, R=F; 3e, R = Cl; 3f, R = Br; 3 g, R = NO2) was synthesized by the treatment of N-(3-nitrophenyl)-N'-(4-R-C6H4)oxamides (2a−g) with [Zn(OAc)2(H2O)2] in a 2:1 molar ratio in the presence of four equivalents of [nBu4N]OH to study the influence of electron-withdrawing and electron-donating groups R on the electronic properties of 3a−g. The structures of 3c,f in the solid state were determined by single crystal X-ray structure analysis confirming the tetrahedral environment around Zn(II) set-up by the respective oxamato ligands. The calculated electrostatic potentials of 3f rationalize the formation of C–H⋅⋅⋅Br–C and C-Br⋅⋅⋅π contacts resulting in the formation of a chain structure. Complexes 3a–g show characteristic LLCT (π → π *) bands in their UV–Vis spectra, which were additionally confirmed by TD-DFT calculations. DFT calculations confirm that the Zn(II) orbitals neither contribute to the HOMO nor LUMO orbitals, since they are mainly localized on the ligands. The thermal decomposition behavior of 3a−g was performed by thermogravimetric analysis and differential scanning calorimetry and the results showed that the complexes are thermally stable. Strong photoluminescence was observed in complexes 3a−g at ambient temperature both in solid state and in solution and the complexes making them good candidates for potential luminescent materials.

Tautomerism in pyridinyl methyl β-diketones in the liquid and the solid state; a combined computational and experimental study

Three 1-(n-pyridinyl)butane-1,3-diones (nPM) (n = 2, 3, and 4) molecules were synthesized and their molecular structure, tautomerism, conformational stability, and intramolecular hydrogen bonding (IHB) of cis-enol forms, was investigated by a combination of computational and experimental methods. Density functional theory (DFT) calculations were used and the Atoms in Molecules (AIM) analysis indicated an intramolecular hydrogen bond strength as 17.9–20.3 kcal/mol using the B3LYP/6–311++G(d,p) level of theory. The calculated structures, NBO, and intramolecular hydrogen bond strengths for the stable cis-enol forms of nPM molecules were compared with each other and with those of acetylacetone (AA) and benzoylacetone (BA). The single crystal X-ray structure of 4PM confirmed that the tautomer with the OH group next to the pyridine ring best describes the structure in the solid-state. The vibrational bands of the title molecules were assigned to the corresponding normal modes, and the equilibrium between the two cis enol tautomers was estimated by means of IR, Raman and UV/Vis spectroscopy.

Synthesis, single crystal X-ray structure determination, Hirshfeld surface analysis, interaction energies, and density functional theory calculations of N,N'-(cyclohexane-1,4-dicarbonothioyl)bis(4-methylbenzamide)

The present research offers convenient synthesis, molecular and crystal structures of C2 symmetric N,N'-(cyclohexane-1,4-dicarbonothioyl)bis(4-methylbenzamide). The synthesized bis-amide crystallized in monoclinic crystal system, having space group of P 21/c with a = 17.8669 (14) Å, b = 6.3495 (5) Å, c = 9.6195 (7) Å, β = 101.567 (8)°, Z = 2 and V = 1069.13 (15) Å3. The asymmetric unit contains cyclohexane ring located on an inversion center, one dicarbonothioyl and one methylbenzamide group. In the crystal structure, the N–H···O, C–H···O and C–H···S hydrogen bonds link the molecules, enclosing R21(6), R22(16) and R22(22) ring motifs, into three-dimensional architecture. Hirshfeld surface (HS) analysis revealed the prevailing significance of hydrogen bond contacts. HS analysis suggested prominent contributions for crystal packing encompasses H…H (49.6%), H…C/C…H (18.9%) and H…S/S…H (16.0%). Hydrogen bonding and van der Waals contacts are the dominant interactions in the crystal packing. The respective volume of the crystal voids and the percentage of free spaces in the unit cell is calculated as 117.87 Å3 and 11.02% indicating the absence of any large cavity within the crystal and the associated stability of the crystal. Evaluation of the electrostatic, dispersion and total energy frameworks revealed that stabilization is dominated by dispersion energy contribution. Moreover, optimized molecular structure, using density functional theory at B3LYP/6-311G(d,p) level, were compared with the experimentally determined ones. HOMO–LUMO energy gap was determined, frequencies and molecular electrostatic potential surface were calculated at the B3LYP/6–311G level to predict sites for electrophilic and nucleophilic attacks. The significant charge polarity, half molecule spread of HOMO and LUMO impart bis-amide nucleophilic as well as electrophilic behavior with relative potency depending upon the nature of the attacking molecule.

Isolation and Reactions of Imidoyl Fluorides Generated from Oxime Using the Diethylaminosulfur Trifluoride/Tetrahydrofuran (DAST-THF) System.

Fluorination of oximes with the relatively mild diethylaminosulfur trifluoride/tetrahydrofuran (DAST-THF) system affords imidoyl fluorides. These compounds were isolated, and their structures were confirmed by X-ray single-crystal structure analysis. Reaction of imidoyl fluorides with various nucleophiles efficiently afforded amides, amidines, thioamides, and amine derivatives in high yields. Furthermore, one-pot reaction of in situ generated imidoyl fluorides from oximes was also applicable to efficient synthesis of these products. The oxime stereochemistry and acid-labile protecting group remained intact in this system.

Single crystal structure feature of a new 1D-coordination polymer of Mn (II); antioxidant activity and protective effects on BLC (both in enzyme activity and in structure)

A new polymer of Mn (II) formulated as [(NIH) (Cl) Mn1 (µ-NIH)2 Mn2(Cl)) (H2O)2] [(NIH) (H2O) Mn3 (µ-NIH)2Mn4(H2O)3]n.6Cl·4H2ONIH, where NIH = 4-Pyridinecarboxylic acid hydrazide = Isoniazid = Isonicotinic acid hydrazide has been synthesized and characterized by elemental analysis, Fourier-transform infrared spectroscopy) FT-IR (, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Powder X-ray Diffraction(PXRD), and single crystal X-ray structure (SC-XRD). SC-XRD results revealed two 1D anionic coordination polymers which are accompanied by four water molecules, one isoniazid molecule, and six chlorine ions. Parallelepiped light orange crystals of Mn complex crystallize in a triclinic system with space group P1. Centers of Mn1, Mn2, Mn3, and Mn4 adopted slightly distorted octahedral. The antioxidant behavior of the Mn complex was tested through a DPPH assay and found that the Mn complex has a good performance in decolorizing the DPPH solution, so it reduces DPPH activity at a concentration of 50 mg L−1 to about 82%. Reactive oxygen species can cause oxidative stress in organisms. Catalase as a valuable antioxidant enzyme can play a protective role. Spectral techniques were used to investigate the effect of the Mn complex on the structure and function of bovine liver catalase (BLC). The catalytic activity of the BLC was significantly improved with the Mn complex. Fluorescence and CD results showed that this complex can induce the environmental changes of amino acid residues (especially Trp) and increase the stability of the secondary structure of the BLC by increasing the α-helix. The interaction process was spontaneous and exothermic, and the most important forces involved in it were van der Waals forces and hydrogen bonds.

Pd(II)-Catalyzed Directing-Group-Aided C–H Arylation, Alkylation, Benzylation, and Methoxylation of Carbazole-3-carboxamides toward C2,C3,C4-Functionalized Carbazoles

AbstractWe report the Pd(II)-catalyzed β-C–H arylation, alkylation, benzylation, and methoxylation of carbazole-3-carboxamide and carbazole-2-carboxamide substrates, assisted by the bidentate directing groups 8-aminoquinoline or 2-(methylthio)aniline, and construction of C2,C3,C4-functionalized carbazole motifs. The Pd(II)-catalyzed β-C–H arylation reaction was attempted using different directing groups such as 8-aminoquinoline, 2-(methylthio)aniline, 4-amino-2,1,3-benzothiadiazole, 4-methoxyquinolin-8-amine, and butan-1-amine. Through optimization of the reactions, 8-aminoquinoline and 2-(methylthio)aniline were found to be suitable directing groups and, especially, 2-(methylthio)aniline was found to be an efficient directing group in the Pd(II)-catalyzed β-C–H arylation, alkylation, and methoxylation of carbazole-3-carboxamide, carbazole-2-carboxamide substrates. An ample number of β-C–H arylated, alkylated, benzylated, and methoxylated carbazole-3-carboxamides were synthesized. The structures of representative β-C(2)–H arylated carbazole and β-C(2)–H methoxylated carbazole motifs were unequivocally confirmed by single-crystal X-ray structure analysis. Given the wide range of applications of carbazoles in chemistry, materials sciences, and medicinal chemistry and there have been constant efforts for developing new methods for synthesizing functionalized carbazoles. This work contributes to the expansion of the library of C2,C3,C4-functionalized carbazole motifs through a Pd(II)-catalyzed directing-group-aided site-selective β-C–H activation and functionalization of carbazole-3-carboxamides.

Immobilization of Phosphamide on the TiO2 Surface for Heterogeneous Phase Catalytic Appel Reaction

Global consumption of triphenylphosphine (Ph3P) for phosphorus-mediated organic synthesis and production of the dead-end triphenylphosphine oxide (Ph3PO) waste is exceptionally high. Recycling Ph3PO and/or use of it as a reaction mediator gained significant attention. On the other end, phosphamides, traditionally used as a flame redundant, are stable analogues to Ph3PO. Herein, via a low temperature condensation reaction of methyl 4-(aminomethyl)benzoate (AMB) and diphenyl phosphinic chloride (DPPC), methyl 4-((N,N-diphenylphosphinamido)methyl)benzoate (1) has been synthesized and hydrolysis of the ester functional group of 1 leads to a phosphamide with a carboxylate terminal, 4-((N,N-diphenylphosphinamido)methyl)benzoic acid (2). The presence of phosphamide functionality (NH─P═O) in 2 can be confirmed by its characteristic Raman vibration at 999 cm-1 with expected P-N and P═O bonds distances from the single-crystal X-ray structure. In-situ hydrolysis of [Ti(OiPr)4] in the presence of 2 followed by hydrothermal heating results in immobilization of 2 on a ca. 5 nm TiO2 surface (2@TiO2). The covalent attachment of 2 via coordination through the carboxylate terminal to the TiO2 nanocrystal's surface has been established via multiple spectroscopic and microscopic studies. 2@TiO2 is further used as the heterogeneous mediator for the catalytic Appel reaction, halogenation of alcohol (typically mediated by phosphine), with a fair catalytic conversion and a recorded TON up to 31. The major advantage of the heterogeneous approach studied herein is the recovery of used 2@TiO2 from the reaction mixture via centrifugation only leaving the organic product in the supernatant, which is limiting in Ph3P-mediated homogeneous catalysis. Time-resolved Raman spectroscopy confirms amino phosphine as the active species formed in-situ during the catalytic Appel reaction. Post-catalytic characterization of the material recovered after catalysis from the reaction mixture confirms the chemical integrity and that can further be utilized for another two catalytic runs. The developed reaction scheme showcases the use of a phosphamide as a reactive analogue to Ph3PO for an organic reaction in a heterogeneous approach, and the same strategy can be explored further as a general scheme for other phosphorus-mediated reactions.

Uncovering John Holliday’s industrial dye synthesis patented in 1865

Holliday’s industrial dye synthesis of 1865 was repeated by heating aniline hydrochloride with nitrobenzene and the products were characterised by modern spectroscopic methods. A red dye was isolated in low yield and characterised by an X-ray single-crystal structure determination as 9-phenyl-3-anilinophenazone-2-anil. The structure was identical to that made 93 years later in 1958 by the oxidation of 2-aminodiphenylamine hydrochloride with FeCl3 followed by heating the two products with aniline. An X-ray single-crystal structure determination was obtained for an isomer of anilinoaposafranine. A proposal is made that 9-phenyl-3-anilinophenazone-2-anil, isolated from Holliday’s synthesis, arises via the oxidation and dimerisation of 2-aminodiphenylamine with hot nitrobenzene so there is a common intermediate in both syntheses.

Unprecedented formation of bis-calix[5]phyrins centrally linked with pyrene subunits

A [3+2] acid-catalyzed condensation of a tetra-functionalized pyrene fluorophore (4) with dipyrromethane dicarbinol (5) resulted in the unprecedented formation of two bis-calix[5]phyrins (bis-calix[5]-1 and bis-calix[5]-2). The solution state structure of both bis-calix[5]phyrins was found to be similar with slight variations as confirmed by NMR spectral studies. Interestingly, two different linkages between the pyrene subunits with dipyrromethane dicarbinols led to two different calix[5]phyrin systems. Although the optical features seem to be similar, the single crystal X-ray structure obtained for bis-calix[5]-1 provided the structural proof showing a non-planar, half-chair conformation with two meso-sp3 carbons. DFT studies were carried out to compare the HOMO-LUMO energy levels of both bis-calix[5]phyrins with the targetted conjugated bis-macrocycle (bis-N[Formula: see text]. Further, both the calix[5]-phyrins showed high Stokes shift (5404 cm[Formula: see text] and fluorescence quantum yield efficiency of around 90%.

Synthesis of Hexahydropyrrolo-isoquinolines by 1,3-Dipolar cycloaddition of tetrahydroisoquinolines and cinnamaldehydes

A new method is described for the synthesis of hexahydropyrrolo-isoquinolines through the 1,3-dipolar cycloaddition of cinnamaldehydes with azomethine ylides generated from cinnamaldehydes and tetrahydroisoquinolines. The carbonyl CO groups of cinnamaldehydes serve as the precursor for the generation of azomethine ylides and the CC double bonds of cinnamaldehyde act as the dipolarophiles in the cycloaddition. The key features are easily available substrates, good functional group tolerance and mild reaction conditions. The relative configurations of products are confirmed by X-ray single crystal structure analysis, and a possible mechanism is proposed. A gram-scale experiment and some chemical transformations were conducted to show the synthetic utility of this approach. Finally, a plausible mechanism was proposed to clarify the formation of products with different configurations.

Synthesis of novel 2- and 8-substituted 4-amino-7-chloroquinolines and their N-alkylated coupling products

The synthesis of a series of 2- and 8-substituted 4-amino-7-chloroquinolines is presented. Starting from 4,7-dichloroquinolines, the chloro in the 4-position can be effectively substituted using amino alcohols to yield novel analogues of the antimalarial (hydroxy)chloroquine. Both short-chain (2-aminoethanol) and long-chain (5-[ N-ethyl- N-(2-hydroxyethyl)amino]-2-aminopentane) coupling partners can be used. While ketone and nitro functionalities were found to be incompatible with the coupling conditions, electron-donating amino and dimethylamino substituents were tolerated. In addition to characterization in solution using multinuclear NMR spectroscopy and high-resolution mass spectrometry, single-crystal X-ray structures are presented of two 4,7-dichloroquinolines as well as three of the N-alkylated products including a unique species in which a pyrrole heterocycle formed at the 2-position of the quinoline subunit and a rare example of a 4-aza-1,10-phenanthroline.

Polymorphic triphenylamine derivative showing aggregation-induced emission and high-contrast mechanical force-induced blue shift

Mechanical force-induced, high-contrast blue-shift luminescent mechanochromic (MC) molecules have rarely been reported. Herein, we designed and synthesized an AIE luminogens (AIEgens) triphenylamine derivative N, N-diphenyl-4-(6-phenyl-[2,2′-bipyridin]-4-yl)aniline (DPTPA). Three different emission wavelengths from blue crystals (B-DPTPA), sky-blue crystals (S-DPTPA), and green crystals (G-DPTPA) were obtained by culturing the crystals under different crystallization conditions. All three crystal polymorphs showed high solid luminescent efficiency, each of which was sensitive to external pressure and was accompanied by significant fluorescence blue shift. Under a mechanical force, B-DPTPA shows a 12 nm blue shift, S-DPTPA fluorescence color changed from sky-blue to blue with an increase emission and G-DPTPA changed its color from green (510 nm) to sky-blue (428 nm) with an 82 nm blue shift. Such obvious color change and large blue shift were rarely been reported. Characterization of the photophysical properties, theoretical calculations, hydrostatic pressure, powder X-ray diffraction and X-ray single crystal structures showed that three crystal polymorphs of DPTPA originated from single molecules, space interactions, molecular pairs (dimers), and the blue shift of B-DPTPA, S-DPTPA, G-DPTPA were ascribed to the solid-state morphology transition from crystal to amorphous due to the destruction of space interactions and dimers. This study provides the relationship between the molecular packings and the blue shift emission of AIEgens materials under mechanical forces is understood in the molecular level.

The 2′-C-methylribonucleoside of 5-aza-7-deaza-7-iodoguanine: Hydrogen and halogen bonding in nucleoside crystals, synthesis and physical properties

The single-crystal X-ray structure of the 5-aza-7-deaza-7-iodoguanine 2′-C-methylribonucleoside 1 is described. The nucleoside was synthesized by stereoselective nucleobase anion glycosylation, yielding the protected nucleoside (70%), which was then deprotected to 1. By the same route, the non-iodinated 2′-C-methylribonucleoside 2 was obtained. In solution, the CD-spectrum of the iodinated 2′-C-methylribonucleoside 1 displays an almost mirror-like Cotton effect compared to the non-halogenated 2, revealing the strong impact of the iodo substituent to the molecule. Suzuki-Miyaura cross-coupling of 1 with pyrene boronic acid yielded a dye conjugate. The pyrene conjugate shows solvent dependent exciplex fluorescence. From the single-crystal X-ray structure of 1, conformational parameter were determined in solid state. The molecule shows anti conformation, a C3’-endo (N) sugar pucker and an antiperiplanar orientation of the 5′‑hydroxyl group. Apart from classical hydrogen bonds, nucleoside 1 possesses a halogen bond from the iodo substituent to the sugar oxygen O3’. A Hirshfeld surface analysis supports this finding. Nucleoside 1 forms a regular, tightly packed structure with stacking interactions between nucleobases and among sugar residues. A comparison of crystal packing of the iodinated 2′-C-methylribonucleoside 1 with the corresponding ribo- and 2′-deoxyribonucleosides demonstrates that halogen bonding depends on the sugar structure and determines the connectivity in crystal layers.

Synthetic Model for FRET Constructed from Covalently Linked Porphyrin Dimers through a Pyrene Bridge.

We report the synthesis and characterization of two porphyrin arrays C6F5-PyZnDP and Mes-PyZnDP covalently linked by a pyrene moiety which differs from their substituents at their meso-positions. The key precursor bis-dipyrromethane linked with a pyrene bridge was prepared by the acid-catalyzed condensation of pyrene-1,6-dialdehyde with excess pyrrole. The synthesis of C6F5-PyZnDP was carried out via two different synthetic routes, with one being efficient over the other. Therefore, the superior route was employed for the synthesis of C6F5-PyZnDP and Mes-PyZnDP. Both the free base and metalated diporphyrins show bathochromically shifted absorption and intense red emission due to the extended π-conjugation through pyrene and porphyrins. The single-crystal X-ray structure reveals an orthogonal orientation of pyrene in between the two planar porphyrins and a slipped stacked packing arrangement in the crystal structure with large meso-meso distances. DFT analysis of both the ground state and the excited S1 state of the macrocycles indicates the difference in the HOMO and LUMO contribution in both the states arising from slight twisting from the mean orthogonal position in the excited state. Further, the Förster energy transfer (FRET) efficiencies from pyrene (donor) to the covalently linked Zn-porphyrins (acceptor) are estimated to be 85 and 91% for Mes-PyZnDP and C6F5-PyZnDP, respectively.

Elucidation of Degradation Behavior of Hydroxy Group-Containing Benzodiazepines in Artificial Gastric Juice: Study on Degradability of Drugs in Stomach (III).

The degradation behavior of three benzodiazepines (BZPs)-lormetazepam (LMZ), lorazepam, and oxazepam-with hydroxy groups on the diazepine ring in artificial gastric juice and the effect of storage pH conditions on drug degradability were monitored using an LC/photodiode array detector (PDA) to estimate their pharmacokinetics in the stomach. Although the three BZPs degraded in artificial gastric juice, none could be restored, despite increasing the storage pH, implying that the degradation reaction was irreversible. As for LMZ, we discussed the physicochemical parameters, such as the activation energy and activation entropy involved in the degradation reaction as well as the reaction kinetics; one of the degradation products was isolated and purified for structural analysis. In the LMZ degradation experiment, peaks corresponding to degradation products, (A) and (B), were detected through the LC/PDA measurements. Regarding the degradation behavior, we hypothesized that LMZ was degraded into (B) via (A), where (A) was an intermediate and (B) was the final product. Although the isolation of degradation product (A) was challenging, degradation product (B) could be isolated and was confirmed to be "methanone, [5-chloro-2-(methylamino)phenyl](2-chlorophenyl)-" based on structure determination using various instrumental analyses. The compound exhibited axis asymmetry as determined using single-crystal X-ray structure analysis. Because the formation of degradation product (B) was irreversible, it would be prudent to target the final degradation product (B) and LMZ for identification when detecting LMZ in human stomach contents, such as during forensic dissection.

A new lithium barium aluminum oxide fluoride, LiBa2AlO3F2

Single-crystal grains of a new quinary compound, LiBa2AlO3F2, were obtained from a polycrystalline sample prepared by heating a starting binary oxide and fluoride mixture with a composition richer in Li and Al than the stoichiometric composition at 1023 ​K. Single-crystal X-ray structure analysis revealed that LiBa2AlO3F2 crystallizes in an orthorhombic cell (a ​= ​7.9953 (3) Å, b ​= ​11.7763 (4) Å, c ​= ​5.6090 (2) Å, space group Pbcm). Al-centered O tetrahedra form zigzag chains in the c-axis direction by sharing vertex oxygen atoms. An OF4 four-sided pyramid is formed, and a Li atom is situated in the pyramid and near the F4 basement. A Li-OF4 pyramid layer is formed by sharing F atoms of the pyramid at x ∼0 around the (100) plane. Ba atoms are located between the slab of Al–O4 zigzag chains and the Li–OF4 pyramid layer. Rietveld analysis of the powder X-ray diffraction pattern indicated that a single-phase polycrystalline bulk sample of LiBa2AlO3F2 was synthesized from a starting-materials mixture with the stoichiometric composition. The conductivity measured for the sample prepared at 1173 ​K was 2.6 ​× ​10−9 ​S ​cm−1 ​at 301 ​K and 2.9 ​× ​10−6 ​S ​cm−1 ​at 443 ​K, and the Li+ transport number was 99%. LiBa1.94Eu0.06AlO3F2 was synthesized by partial substitution of Eu2+ for Ba2+. A broad emission spectrum with a peak at 610 ​nm and a full-width at half-maximum of 170 ​nm was recorded for this sample under ultraviolet-light excitation at a wavelength of 330 ​nm.

Indolyl imine substituted BODIPY systems; synthesis, photophysical, and biological properties

In the study, 4,6-dimethoxy-2,3-diphenylindole-7-carbaldheyde 2, served as a valuable precursor for the reaction with both aniline and BODIPY-linked aniline, generated novel indolyl-imine Schiff base ligands 3 and 7. These indolyl-imine ligand systems were then employed to create the corresponding N–N six-membered boron complexes, 4 (precursor) and 8. The structure of novel compounds were confirmed by 1H and 13C NMR, and high-resolution mass spectrometry. The final evidences of indolyl-imine 7 and its corresponding boron complex 8 were further supported by the single X-ray crystal structures. Single crystal X-ray diffraction analysis revealed the formation of short “C–H⋯F”, “C–H···π”, “C–H⋯O” and “C–H⋯B” interactions, which led to the impressive supramolecular tubular-like (7) and helical (8) self-assemblies. The investigations of the UV–Vis absorption and fluorescence emission properties of the targeted compounds 4, 7 and 8 were carried out using absorption and fluorescence emission (2D and 3D) spectroscopic techniques. Fluorescence properties of the targeted compounds were found to be solvent-dependent. DFT optimized structures and the TD-DFT calculations were in alignment with the experimental studies. Additionally, the cytotoxic properties of the target compounds were examined in human breast cancer cells, MCF-7 in vitro as preliminary biological study.

Syntheses, Characterization, Crystal Structures and Antimicrobial Activity of Copper(II), Nickel(II) and Zinc(II) Complexes Derived from 5-Bromo-2- ((cychlopentylimino)methyl)phenol

Four new complexes of copper(II), nickel(II) and zinc(II), [CuL2] (1), [Ni3L2(4-BrSal)2(CH3COO)2(CH3OH)2]·2CH3OH (2), [ZnBr2(HL)2] (3) and [ZnL(dca)]n (4), where L is 5-bromo-2-(cychlopentylimino)methyl)phenolate, HL is the zwitterionic form of 5-bromo-2-((cychlopentylimino)methyl)phenol, 4-BrSal is the monoanionic form of 4-bromosalicylaldehyde, dca is dicyanamide anion, were synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy. The structures of the complexes were further confirmed by single crystal X-ray structure determination. Complex 1 is a mononuclear copper(II) compound, with a crystallographic two-fold rotation axis symmetry. The Cu atom is in distorted square planar coordination. Complex 2 is a trinuclear nickel(II) compound, with an inversion center symmetry. The Ni atoms are in octahedral coordination. Complex 3 is a mononuclear zinc(II) compound, while complex 4 is a dca bridged polymeric zinc(II) compound. The Zn atoms are in tetrahedral coordination. The compounds were assayed for their antimicrobial activities.

Syntheses, Characterization, Crystal Structures and Antimicrobial Activity of Copper(II), Nickel(II) and Zinc(II) Complexes Derived from 5-Bromo-2-((cychlopentylimino)methyl)phenol.

Four new complexes of copper(II), nickel(II) and zinc(II), [CuL2] (1), [Ni3L2(4-BrSal)2(CH3COO)2(CH3OH)2]·2CH3OH (2), [ZnBr2(HL)2] (3) and [ZnL(dca)]n (4), where L is 5-bromo-2-((cychlopentylimino)methyl)phenolate, HL is the zwitterionic form of 5-bromo-2-((cychlopentylimino)methyl)phenol, 4-BrSal is the monoanionic form of 4-bromosalicylaldehyde, dca is dicyanamide anion, were synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy. The structures of the complexes were further confirmed by single crystal X-ray structure determination. Complex 1 is a mononuclear copper(II) compound, with a crystallographic two-fold rotation axis symmetry. The Cu atom is in distorted square planar coordination. Complex 2 is a trinuclear nickel(II) compound, with an inversion center symmetry. The Ni atoms are in octahedral coordination. Complex 3 is a mononuclear zinc(II) compound, while complex 4 is a dca bridged polymeric zinc(II) compound. The Zn atoms are in tetrahedral coordination. The compounds were assayed for their antimicrobial activities.