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Here, an unprecedented phenomenon in which 7‐coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated H2O molecules, form micellar cubic mesophases at room temperature, creating body‐centered cubic (BCC)‐type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self‐assembling behavior of 6‐coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions. Since the magnetic and luminescent properties of different lanthanides vary, adding arbitrary functions to spherical arrays is possible by selecting suitable lanthanides to be used. The method developed in this study using 7‐coordinate lanthanide metallomesogens as building blocks is expected to lead to the rational development of micellar cubic mesophases. [ABSTRACT FROM AUTHOR]

We have synthesized thirteen novel metallomesogens based on dithiolene nickel complex showing π-acceptor properties: (o-C12OPhO)4DTNi (1), (m-C12OPhO)4DTNi (2), (p-C12OPhO)4DTNi (3), [o,m-(C12O)2PhO]4DTNi (4), [m,m′-(C12O)2PhO]4DTNi (5), [p,m-(CnO)2PhO]4DTNi (6: n = 10(a), 12(b), 14(c), 16(d)) and Cl-[p,m-(CnO)2PhO]4DTNi (7a–d). By using plarizing microscopic observations, differential scanning chalorimetry, and temperature-variable X-ray diffraction studies, the columnar liquid crystalline mesophases were established for the 6a–d and 7a–d derivatives. It was also revealed from the electrochemical measurements that each of the complexes of 1–7 showed good π-acceptor abilities. In particular, the derivatives, Cl-[p,m-(CnO)2PhO]4DTNi (7a–d), exhibit the most positive reduction potential from +0.08 to +0.07 V versus. SCE. [ABSTRACT FROM AUTHOR]

Abstract Here, an unprecedented phenomenon in which 7‐coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated H2O molecules, form micellar cubic mesophases at room temperature, creating body‐centered cubic (BCC)‐type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self‐assembling behavior of 6‐coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions. Since the magnetic and luminescent properties of different lanthanides vary, adding arbitrary functions to spherical arrays is possible by selecting suitable lanthanides to be used. The method developed in this study using 7‐coordinate lanthanide metallomesogens as building blocks is expected to lead to the rational development of micellar cubic mesophases.

A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a complex matrix nanoplatform for the fabrication of a high-performance electrochemical hybrid sensor. Three representative paste electrodes, which differ by the weight ratio between Zn(II) metallomesogen and carbon nanotubes (CNT), i.e., PE_01, PE_02 and PE_03, were obtained by mixing the materials in different amounts. The composition with the largest amount of CNT with respect to Zn complex, i.e., PE_03, gives the best electrochemical signal for uric acid detection by cyclic voltammetry in an alkaline medium. The amphiphilic structure of the Zn(II) coordination complex likely induces a regular separation between the metal centers favoring the redox system through their reduction, followed by stripping, and is characterized by enhanced electrocatalytic activity towards uric acid oxidation. The comparative detection of uric acid between the PE_03 paste electrode and the commercial zinc electrode demonstrated the superiority of the former, and its great potential for the development of advanced electrochemical detection of uric acid. Advanced electrochemical techniques, such as differential-pulsed voltammetry (DPV) and square-wave voltammetry (SWV), allowed for the highly sensitive detection of uric acid in aqueous alkaline solutions. In addition, a good and fast amperometric signal for uric acid detection was achieved by multiple-pulsed amperometry, which was validated by urine analysis. [ABSTRACT FROM AUTHOR]

The mesomorphism is reported of a discotic complex of gold(III) that is amphiphilic on account of the presence of both hydrocarbon and fluorocarbon chains. The all-hydrocarbon analogue of the complex shows only a columnar hexagonal phase between the melting and clearing points, whereas this new, amphiphilic example shows a nematic phase between a columnar rectangular phase and a columnar hexagonal phase. The nature and formation of the nematic phase are discussed and it is proposed to be a columnar nematic formed as a result of frustration driven by the amphiphilic nature of the complex. [ABSTRACT FROM AUTHOR]

A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a complex matrix nanoplatform for the fabrication of a high-performance electrochemical hybrid sensor. Three representative paste electrodes, which differ by the weight ratio between Zn(II) metallomesogen and carbon nanotubes (CNT), i.e., PE_01, PE_02 and PE_03, were obtained by mixing the materials in different amounts. The composition with the largest amount of CNT with respect to Zn complex, i.e., PE_03, gives the best electrochemical signal for uric acid detection by cyclic voltammetry in an alkaline medium. The amphiphilic structure of the Zn(II) coordination complex likely induces a regular separation between the metal centers favoring the redox system through their reduction, followed by stripping, and is characterized by enhanced electrocatalytic activity towards uric acid oxidation. The comparative detection of uric acid between the PE_03 paste electrode and the commercial zinc electrode demonstrated the superiority of the former, and its great potential for the development of advanced electrochemical detection of uric acid. Advanced electrochemical techniques, such as differential-pulsed voltammetry (DPV) and square-wave voltammetry (SWV), allowed for the highly sensitive detection of uric acid in aqueous alkaline solutions. In addition, a good and fast amperometric signal for uric acid detection was achieved by multiple-pulsed amperometry, which was validated by urine analysis.

Three new series of photoluminescent nickel(II) metallomesogens, [NiL]; H2L = N,N′-Bis(4-n-alkoxysalicylidene)-4-fluoro/bromo/chloro-1,2-diaminobenzene (n = 12, 14, 16) based on 'salphen' ligands have been synthesised and their mesomorphic and photophysical properties explored. The complexes, isolated as orange microcrystalline solids were characterised by elemental analyses, FT-IR, 1H NMR and UV-visible spectroscopy. Thermal studies show all the compounds to be enantiotropic liquid crystals displaying columnar mesophase over a wide temperature range. Electronegativity and steric requirement of the halogen substituent at the ligand's spacer remarkably influence the 2-D packing of the columns in the lattice in these complexes controlling the supramolecular mesomorphic order and photoluminescence. The mesophase behaviour of the fluoro-substituted complex is characterised by a transition from a columnar oblique (p1) to columnar rectangular (p2mm) phase, former stable till ambient temperature. The chloro and bromo analogues, on the other hand, displayed exclusively columnar rectangular (p2mm) mesophase with the former transforming into a glassy state and latter into a crystalline phase during cooling to ambient temperature. Molecular model based on interdigitated anti-parallel and back to back arrangements in the different columnar mesophase are proposed on the basis of X-ray diffraction (XRD) studies. The complexes emit in the blue region when excited with near UV wavelength. [ABSTRACT FROM AUTHOR]

Abstract: A series of new mononuclear multifunctional lanthanide(III)‐Schiff base complexes have been synthesized and characterized by elemental analyses, FTIR, 1H NMR and UV/Vis spectroscopy. Potentially tridentate, the Schiff‐base ligand is based on a ‘salicyldimine’ core with a long and flexible alkoxy group which coordinates to lanthanide ions in its zwitterionic form via the phenolic‐oxygen with the proton shifted to the imine‐nitrogen. The chelate nitrato groups complete a nine‐coordinate geometry. The ligand is non‐mesomorphic, while coordination to Ln3+ ion induces a liquid crystalline behavior. The complexes exhibited a thermally stable highly viscous partially bilayer smectic Ad phase in the 45‐135°C temperature range. The molecular organization of the complexes in the mesophase is conjectured to be based on a cylindrical‐like dimeric structure with the three alkoxy group pointing up and three pointing down assembling laterally into a lamellae. The Schiff base ligand is a blue light emitter exhibiting a broad emission maximum at 435 nm while the lanthanide complexes show an intense green emission. The Tb3+ complex, interestingly, also showed mesophase luminescence. The ligand and its complexes of La3+, Dy3+ and Yb3+ exhibited a significant second order non‐linear optical (NLO) activity representing the first example of lanthanidomesogens to exhibit such behaviour. [ABSTRACT FROM AUTHOR]

We have synthesized a series of six novel bis(β-diketonate)copper (II) complexes, 1a, 1b, 2a, 2b, 3a, and 3b, substituted by two bulky substituents in the short molecular axis direction to investigate their mesomorphism. The m,p,m'-trimethoxylphenyl-substituted derivatives, 2a and 2b, and the m,p-dimethoxylphenyl-substituted derivatives, 3a and 3b, did not show mesomorphism, whereas each of the p-methoxyphenyl-substituted derivatives 1a and 1b only showed a nematic phase, which was revealed from polarizing microscopic observations. We established from X-ray diffraction and Z-value calculations that each of the crank-like derivatives 1a and 1b forms a rectangular parallelepiped dimer and shows a biaxial nematic phase. [ABSTRACT FROM AUTHOR]

Two new square pyramidal iron(III)-complexes of ‘salen’-type Schiff base ligands containing 4-substituted long alkoxy arms on the aromatic rings, [Fe(4-C16H33O)2salcn)]Cl and [Fe(4-C16H33O)2salophen)]Cl {salcn = N,Nʹ-cyclohexanebis(salicylideneiminato) and salophen = N,Nʹ-phenylenebis(salicylideneiminato)}, have been successfully synthesised, and their mesomorphic property investigated. The ligands and complexes were characterised by elemental analyses, UV–Vis, FT-IR, ESI–MS,1H and13C NMR (for ligands only). The phase behaviour of the iron(III) complexes were ascertained by differential scanning calorimetry, polarising optical microscopy and variable temperature PXRD study. Ligands are non-mesomorphic, however, mesomorphism got induced upon complexation with the iron(III) centre. X-ray diffraction study revealed a layer-like arrangement of the five coordinated mesomorphic iron(III) complexes. The mesophase is stable over a wide range of temperature. The density functional theory calculations were carried out using Gaussian 09 program at B3LYP level using unrestricted 6–31G (d, p) basis set to obtain the optimised geometry of the iron(III) complexes. [ABSTRACT FROM AUTHOR]

Kinetic models for the ‘molecular’ mechanochemical syntheses of α- and β-dialkyl 2,2′-bipyridyl-4,4′-dicarboxylate complexes of palladium (PdLnI2, wherenspecifies the number of carbons in the alkyl chain of the ligand and α and β refer to the substitution of the alkyl chain) are explored. The Johnson–Mehl–Avrami–Yerofeev–Kolmogrov (JMAYK) model was determined to best fit the data obtained via1H NMR spectroscopic analysis of the reaction mixtures over time. A rate enhancement, and corresponding increase in the Avrami exponent, was observed when the complex formed was liquid crystalline at milling temperatures. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Coordination compounds present significant advantages of diversity and tunability. • These materials provide efficient method for functional-molecular-based materials. • Development of coordination metal complex materials paves the way for new research based on molecular ferroelectrics. Ferroelectric materials exhibit spontaneous electric polarization, which can be switched by an external electric field. Owing to their intrinsic abundance of electrical, mechanical, and thermal properties such as pyroelectric and piezoelectric properties, ferroelectric materials can be used in various functional devices, such as data storage devices, sensors, mechanical actuation devices, and other optoelectronic applications. Although molecular-based ferroelectric materials, such as pure organic/inorganic compounds, have piqued significant research interest, unique ferroelectrics based on coordination metal complexes have not been studied in detail. These materials have recently received significant attention because they offer an efficient method for fabricating functional molecular-based materials due to their characteristic intrinsic electronic/spin states. Thus, this review discusses recent advances in the literature on ferroelectricity in metal complexes. We believe that this review will contribute to fabricating novel ferroelectric materials based on metal complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metallomesogens based on 4-phenylpyridine complexes of silver(I) are made. • Complexes characterised by microscopy, DSC and small-angle X-ray methods. • Cubic and columnar hexagonal phases are observed. • Mesomorphism is compared with analogous silver salts and ionic materials. • Significant stabilisation of the columnar hexagonal phase is observed. 3,4-Dialkoxyphenylpyridine complexes with silver dodecyl sulfate or silver triflate are liquid crystalline. The complexes are polycatenar and show one or both of a cubic and a columnar hexagonal phase depending on the chain length of the dialkoxyphenylpyridine and the anion associated with the silver. Their mesomorphism is compared both with the analogous and very well-studied silver complexes of dialkoxystilbazole ligands as well as closely related N -phenylpyridinium analogues. The slightly shorter nature of the dialkoxyphenylpyridines is important in determining the mesomorphism when compared to the dialkoxystilbazole complexes, whereas there are appreciable differences with the N -phenylpyridinium salts. The notable stabilisation of the Col h phase remains a feature of all three families of materials. [ABSTRACT FROM AUTHOR]

Copper(II) complexes containing chiral centres and functionalised with citronellyl end groups were synthesised. Isomerisation of citronellyl double bond was exploited to decrease the melting temperature of the complexes and improve their solubility in organic media. The chiral metallomesogens were successfully used to produce induced cholesteric solutions in commercial nematic liquid crystals also in high concentrations. Transparent and coloured thin films were easily obtained showing good reflective properties across the visible spectrum. The rheological behaviour of the nematic and the cholesteric phases was investigated. The nematic system showed the characteristics of a tumbling phase with a very peculiar transient behaviour. The cholesteric samples also showed a very unusual, flow-history-dependent transient behaviour. The viscosity trend presumably indicates a flow-induced orientation of the cholesteric superstructure, thus opening the way to the possibility of tuning the yield stress level of the material. The results support the potentiality of these compounds for applications in light reflecting technology. [ABSTRACT FROM PUBLISHER]

Dialkyl 2,2′-bipyridyl-4,4′-dicarboxylate (Lβn, where βnrefers to the number of carbons in β-substituted alkyl chain) complexes including PtLβ16Cl2, CdLβ16Cl2, [AgLβnNO3] and the dodecylsulfate salt [AgLβn2](DOS) were produced at reduced cost and in shorter times, compared to traditional solvent-based methods, by mechanochemical reaction in the absence of solvent. PtLβ16Cl2and the [AgLβn2](DOS) complexes are the first mesogenic transition metal complexes to be produced via ball milling. The effectiveness of a simple ligand modification, β- versus α-attachment of the alkyl functionalities to the ligand, is presented as a highly effective method for increasing the stable temperature range of a variety of metallomesogens and for producing sub-room-temperature liquid crystals. [ABSTRACT FROM AUTHOR]

Novel nickel (II) phthalocyanines carrying four branched thia- and oxy-oligo(ethyleneoxy) groups on peripheral and non-peripheral positions have been synthesized from the corresponding phthalonitrile derivatives. The new compounds have been characterized by elemental analysis, mass spectrometry, infrared, nuclear magnetic resonance, and ultraviolet-visible spectroscopy. The spectroscopic properties and aggregation behaviors of these phthalocyanine complexes have been studied in different solvents and concentrations. The mesogenic properties of these new materials have been determined by differential scanning calorimetry, optical polarized microscopy and X-ray diffraction investigations. The effects of the substituents' position (α or β) and the nature of the linker heteroatom (O or S) on the mesogenic properties of the synthesized nickel (II) phthalocyanines have also been explained. [ABSTRACT FROM AUTHOR]

Highlights: [•] A series of oxovanadium(IV) complexes of bidentate [N,O] donor Schiff-base ligands have been synthesized. [•] The ligands and complexes are all thermally stable exhibiting smectic mesomorphism. [•] The ligands show SmC and an unidentified SmX phase reminiscent of soft crystal. [•] Oxovanadium complexes mostly showed SmA phase. [•] Interestingly, the complexes with C10 and C12 alkoxy chain length exhibited additionally SmC phase also. [Copyright &y& Elsevier]

Highlights: [•] The state of the art of liquid-crystalline metallodendrimers is reviewed. [•] Designs and properties of metal ion-cored (centre) and metal ion-coated (periphery) LC dendrimers. [•] Towards multifunctional hybrids: Janus metallodendrimers, dendronized polymetallic systems (clusters and nanoparticles). [ABSTRACT FROM AUTHOR]

A new series of Schiff's base mesogenic ligands with a polar methyl ester as an end group, methyl 4-(4'-(alkoxy)-2 hydroxybenzylideneamino) benzoates, CnLH (n = 6, 8, 10, 12, 14, 16) and their copper(II) and nickel(II) complexes have been synthesized. They were characterized by elemental analyses, Fourier transform infrared (FT-IR), ¹H and 13C nuclear magnetic resonance, and UV-VIS spectroscopy. The mesomorphic properties of these compounds were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The ligands exhibit an enantiotropic SmA mesophase with a high-temperature range and thermal stability. The square planar copper(II) complexes show enantiotropic SmA mesophase, but the nickel(II) complexes are nonmesogenic in nature. The thermal stability of the compounds was also determined by thermo gravimetric analyses. Density functional theory (DFT) calculations were performed using GAUSSIAN-03 program at B3LYP level to obtain the stable electronic structure of the ligand and their metal complexes. [ABSTRACT FROM AUTHOR]

Dialkyl 2,2′-bipyridine-4,4′-dicarboxylate derivatives are non-mesogenic ligands capable of supporting liquid crystalline phase formation when coordinated with a variety of metals. Herein is described a preliminary study on altering stable temperature ranges of thermotropic mesophases through metal centre selection and ligand modification. Characterisation of non-mesogenic CdLα nCl2complexes and mesogenic ReLα n(CO)3Br and PtLβ nCl2derivatives are presented (Lα nis the ligand withα-attachment of alkyl chains, Lβ nis the ligand withβ-attachment of chains andnis the number of carbons in the alkyl chain). Synthetic procedures and characterisation of the products by differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy and variable temperature X-ray diffraction are presented. [ABSTRACT FROM PUBLISHER]

Abstract: A series of tetradentate Schiff base metallomesogenic diols and their model compounds were synthesized from two simple dihydroxy benzenes. The metallomesogenic diol was constructed from three ring containing mesogen linked through ester and azomethine with terminal hydroxy group. This upon complexation with copper(II) formed metallomesogenic diol with varing terminal chain length. The related model metallomesogenic compounds were also synthesized with varying chain length with terminal methyl group and compared the properties with metallomesogenic diols. Extensive characterization of all metallomesogenic compounds and intermediates were carried out by FT-IR, 1H &13C NMR, EPR, VSM, Mass (EI and FAB) and UV–Vis spectroscopy. Hot stage polarizing microscope, Differential scanning calorimetry was used to ensure the phase characteristics such as nature of phase, melting and clearing temperatures and phase range. The appearance of enantiotropic smectic A phases indicated high molecular polarizability of the core due to the metal ion. The role of copper(II) ion on mesogens were discussed. [Copyright &y& Elsevier]

A series of materials based on the aroylhydrazinatonickel (II) complex is synthesized and characterized. The molecule in the materials consist of two 4-benzoyloxy-benzene groups and two benzene rings having two or three alkoxy chains containing 6, 8, 10, and 12 carbon atoms attached at the azomethine moiety. The synthesis, characterization by NMR and the phase sequence observed by DSC and polarized light microscopy are presented. Most of the compounds in the series display columnar phases in the temperature range between 100°C and 200°C. The phases observed and their temperature ranges are discussed in terms of the number and position of attached alkoxy chains. [ABSTRACT FROM AUTHOR]

Abstract: A series of tetradentate Schiff base metallomesogenic diols were synthesized from two simple dihydroxy benzenes. The metallomesogenic diol was constructed from three ring containing mesogen linked through ester and azomethine with terminal hydroxy group. This upon complexation with copper(II) formed metallomesogenic diol with varying terminal chain length. A series of metallomesogenic polyurethanes were synthesized using these metallomesogenic diols as chain extenders for the prepolymers based on polytetramethylene glycol (PTMG) of varying molecular weight (M n =650, 2000) and 2,4-toluene diisocyanate (TDI), or 4,4′-methylene bis(phenyl isocyanate) (MDI). The molar ratio of metallomesogenic diol and PTMG were varied in the polyurethane to find their role in liquid crystalline and mechanical properties. Extensive characterization of all metallomesogenic compounds and intermediates were carried out by FT-IR, 1H and 13C NMR, EPR, VSM, Mass (EI and FAB) and UV–visible spectroscopy. Hot stage polarizing microscope and differential scanning calorimetry were used to ensure the phase characteristics such as nature of phase, melting and clearing temperatures and phase range. The appearance of enantiotropic smectic A phases indicated high molecular polarizability of the core due to the metal ion. [Copyright &y& Elsevier]

A series of half-discoid [N2O2]-donor tetradentate alkoxy substituted salicylaldimine ligands, [N,N′-di- (4-n-alkoxysalicylidene)-4-Cl-l,2-diamino-benzene] (L; n = 12, 14, 16 and 18) have been prepared. The reaction of the ‘salphen’-type Schiff base ligand with Zn(OAc)2.4H2O afforded a series of mononuclear zinc(II) complexes. The ligands and the corresponding zinc(II) complexes were characterised by elemental analysis, Fourier transform infrared, proton nuclear magnetic resonance and ultraviolet-visible spectroscopy. Although the ligands are non-mesogenic, columnar mesomorphism is induced upon complexation with the metal. The p2gg symmetry of the rectangular columnar phase is confirmed by variable temperature powder X-ray diffraction study. Two ‘half-disc’-shaped molecules with four alkoxy legs are presumed to self-assemble via a dimeric interaction filling the space. In contrast to the ligands, the zinc(II) complexes all exhibited moderately intense green emission at room temperature both in solution and in the solid state. Density functional theory calculation, carried out using a DMol3 program, revealed a distorted square planar geometry for the complexes. The mesomorphic and photoluminescence property of the zinc complexes are collated as a function of spacer substituent, as well as alkoxy carbon chain length. [ABSTRACT FROM AUTHOR]

A series of new oxovanadium(IV) Schiff-base complexes of the type [VO(L)2], [L = N-(4-n-alkoxysalicylaldimine)-4′-dodecyloxyaniline, n = 6, 8, 16, and 18] have been synthesized. The compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, UV-Vis, FAB-mass, and magnetic susceptibility measurements. The mesomorphic behavior of the compounds was studied by polarized optical microscopy and differential scanning calorimetry. The compounds are all highly thermally stable exhibiting smectic mesomorphism. Non-electrolytic nature of the complexes was ascertained by solution electrical conductance measurements. Cyclic voltammetry revealed a quasireversible single-electron response for VO(V)/VO(IV) couple. A νV=O stretching mode at ∼970 cm−1 indicates absence of any intermolecular V=O ··· V=O interactions. Density functional theory study was carried out using DMol3 at BLYP/DNP level to determine energy optimized structure revealed a distorted square pyramidal geometry for the vanadyl complexes. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, characterization and mesomorphic properties of a new series of acetate and chloro-bridged dinuclear orthopalladated complexes derived from azobenzene with terminal groups of hexadecyloxy moiety at one end and different polar groups (Me, Cl, F, NO2, CN) at the other end are described. The mesomorphic properties of both the ligands and complexes were investigated by polarizing optical microscopy and X-ray studies to understand the effect of polar group in the nature of mesophase produced. Among the complexes, all chloro-bridged complexes predominantly exhibited SmA phase. However the rare phenomenon of observing mesomorphism in acetato-bridged palladium (II) complexes due its typical open book shape had been realized in substituted acetato-bridged complexes with fluoro and cyano substituents in the ligands. Nitro and cyano substituted ligands only exhibited monotropic Smectic A phase. Model molecular arrangement based on X-ray studies is presented. [Copyright &y& Elsevier]

A new series of oxovanadium(IV) complexes of the type [VOL], L = N, N′-di-(4-n-alkoxysalicylidene)-4-Me-l,2-diamino-benzene (n = 14,16, 18) have been synthesised and their mesomorphic properties investigated. The compounds were characterised by Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, ultraviolet–visible spectroscopy, elemental analyses, solution electrical conductivity measurements and fast atom bombardment mass spectrometry. The phase behaviour of the compounds was examined by differential scanning calorimetry and polarised optical microscopy. The ligands are non-mesogenic, but upon coordination with vanadium(IV), exhibited enantiotropic rectangular columnar mesomorphism. The mesophase symmetry and the molecular organisation in the mesophases were confirmed by variable temperature powder X-ray diffraction study. An interesting phase behaviour exhibiting two types of rectangular columnar phases (Colr1 to Colr2) was observed for the vanadyl complexes, the former (Colr1) being stable down to room temperature. Solution electrical conductivity measurements showed non-electrolytic nature of the complexes. Cyclic voltammetry revealed a single electron quasi-reversible response (VO2+/VO3+) for the complexes. Density functional theory study carried out using the DMol3 program indicated a distorted square pyramidal geometry for the complexes. [ABSTRACT FROM AUTHOR]

Abstract: Two unsymmetrically substituted phthalocyanines bearing six alkoxy moieties (3a) and six alkoxy facing two p-tolyl-sulfonyl(tosyl)amido moieties (3b) were synthesized by cyclotetramerization reactions of corresponding two different phthalonitrile derivatives in the presence of an anhydrous Zn(AcO)2 and strong base. These novel compounds were fully characterized by elemental analyses, IR, 1H and 13C NMR and Mass spectra. The thermal stabilities of the phthalocyanine compounds were determined by thermogravimetric analysis (TGA). The mesogenic properties of these new materials were studied by differential scanning calorimeter (DSC) and optical microscopy. Absorption and emission based spectral characterization were done in THF. The base sensitivity of both compounds was examined with absorbance and fluorescence spectrophotometer in THF. The effect of tosylamido units on thermal stability, and mesogenic, photophysical and base sensitivity properties were discussed by comparing two compounds. [Copyright &y& Elsevier]

A series of salicylaldimine-based copper(II) and oxovanadium(IV) complexes of the type [ML2] (M = Cu and VO, L = N,N′-bis-(4-X-amino phenyl (4′-n-alkoxy)-salicylaldiminato), n = 4, 6; X = Cl, NO2) have been synthesised. The mesomorphic behaviour of the ligands and their complexes was probed by polarising optical microscopy and differential scanning calorimetry. The formation of mesophases was dependent not only on the electronic or the steric factors of the substituents but also on metal centre. The ligands all showed a smectic or nematic mesophase. However, nitro-substituted compounds with (n = 4) lacked any mesomorphism. Complexes (X = Cl, NO2, n = 4, 6 and M = Cu) exhibited smectic A phases. The vanadyl complexes did not show any mesogenicity. Variable temperature magnetic susceptibility measurements were carried out for the copper and vanadyl complexes. The complexes obey the Curie–Weiss law. Cyclic voltammetry showed a single electron quasireversible response for the complexes. Density functional theory analysis study revealed a distorted square planar and square pyramidal geometry for the copper(II) and vanadyl complexes, respectively. At 330 nm excitation, the ligands showed green emission in the solid state (∼ 516–559 nm, Φ = 12–9%) at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: A series of hemi-disc shaped non-mesomorphic tetradentate salicylaldimine ligands [N,N′-di-(4-hexadecyloxysalicylidene)-l,2-diamino-benzene, N,N′-di-(4-hexadecyloxysalicylidene)-4-Me-l,2-diamino-benzene, and N,N-di-(4-hexadecyloxysalicylidene)-4-NO2-l,2-diamino-benzene, (H2L)] were synthesized. Incorporation of nickel(II) in the tetradentate core via reaction with Ni(OAc)2·4H2O afforded a series of four coordinate mesogenic NiL derivatives. The ligands and complexes were characterized by elemental analyses, FT-IR, UV–Vis, FAB-mass, 1H and 13C NMR (for ligands only). The mesomorphic behavior of the complexes were probed by polarizing optical microscopy, differential scanning calorimetry and powder X-ray diffraction technique. The non-mesogenic ligands upon coordination with nickel(II) exhibited monotropic/enantiotropic phase transition showing rectangular columnar mesophases (Colr) with c2mm symmetry. A antiparallel dimeric association forming a disc-like arrangement in the mesophase is proposed on the basis of XRD-study. Solution electrical conductivity measurements are consistent with the non-electrolytic nature of the complexes. At room temperature with 330nm excitation, the complexes showed blue emission both in the solid state (∼481nm, Φ =7%) and in solution (∼456nm, Φ =23%) while the ligands are non-emissive. The DFT study carried out at BLYP/DNP level revealed a distorted square planar structure for the nickel(II) complexes. [Copyright &y& Elsevier]

Recent progress in the synthesis of liquid crystals containing silver is reported and compared. The new silver(I) argentogens are grouped according to the organic ligands coordinated and the related coordination geometries, with an emphasis on the luminescence properties. [ABSTRACT FROM AUTHOR]

Oxovanadium(IV)-Schiff-base complexes, [VOL2] {L = N,N′-bis-(4-X-amino phenyl (4′-n-alkoxy)-salicylaldiminato), n = 10, 18; X = Cl, NO2}, have been synthesized from the interaction of vanadyl (VO2+) and the bidentate [N,O] donor in methanol/ethanol. The compounds were characterized by FT–IR, 1H- and 13C-NMR, FAB-mass spectra, elemental analyses, and solution electrical conductivity. Mesomorphic behavior of the ligands and their vanadyl complexes were probed by polarizing optical microscopy and differential scanning calorimetry. The compounds are thermally stable and exhibit enantiotropic smectic A mesomorphism over the temperature range of 57–231°C. The mesophase–isotropic transition temperatures for the complexes are much higher than the ligands. Melting and clearing points of the compounds did not show any definitive trend with regards to alkoxy chain length or electronegative substituent. Variable temperature magnetic susceptibility measurements of the vanadyl complexes clearly show the absence of exchange interactions among the vanadyl spin centers. Non-electrolytic natures of the complexes were shown by conductometric measurements. A ν(V=O) of ∼970 cm−1 corroborated the absence of any V=O ··· V=O interactions. Density functional theory study carried out using DMol3 at BLYP/DNP level to determine the energy-optimized structure revealed a distorted square pyramidal geometry for the vanadyl complexes. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, liquid crystalline, photophysical and photochemical properties of the peripheral- and non-peripheral-tetra-substituted alkylthio gallium(III) phthalocyanines are reported here for the first time. These novel compounds have been characterized by elemental analysis, UV–Vis, IR and 1H NMR spectroscopy and mass spectrometry. The thermal stabilities of the phthalocyanine compounds have been determined by thermogravimetric analysis. The mesogenic properties of these new materials have been investigated by differential scanning calorimetry, polarized optical microscopy and X-ray diffraction measurements. The investigation of thermotropic behavior showed that all of the new compounds are liquid crystalline over a wide range of temperature. The X-ray diffraction patterns confirm that the phthalocyanines form a hexagonal columnar mesophase. Photophysical (fluorescence and photodegradation quantum yields and fluorescence lifetimes) and photochemical (singlet oxygen quantum yields) properties of these compounds have been investigated in toluene. The fluorescence of the substituted gallium(III) phthalocyanines is effectively quenched by 1,4-benzoquinone. [Copyright &y& Elsevier]

A series of oxovanadium(iv) complexes of the type [VO(L)2], [L = N-(4-n-alkoxysalicylaldimine)-4-hexadecyloxyaniline, n = 8, 10, 12, 14, 16 or 18] have been synthesised and characterised by FT-IR, 1H NMR, 13CNMR, UV-Vis, and FAB mass and magnetic susceptibility measurements. The ligands are coordinated to the vanadyl ion in a bidentate fashion. The mesomorphic behaviour of the ligands and their vanadyl complexes was investigated by polarising optical microscopy and differential scanning calorimetry. The compounds were all highly thermally stable, and their mesomorphic properties were found to depend on the length of the carbon chain. Both the ligands and their higher homologue complexes exhibited a SmC mesophase. In the case of the lower homologues the ligands exhibited the SmC phase but their complexes a SmA mesophase. The mesophase-isotropic transition temperatures for the complexes were significantly higher than those of the ligands. Variable temperature magnetic susceptibility measurements on the vanadyl complexes clearly suggested absence of any exchange interactions among the vanadyl spin centres. Cyclic voltammetry showed a quasi-reversible one-electron response at 0.51 V for the VO(iv)-VO(v) redox couple. Density functional theory studies carried out using DMol3 at the BLYP/DNP level to determine the energy-optimised structure revealed a distorted square pyramidal geometry for the vanadyl complexes, with the alkoxy tails projecting away from one another. [ABSTRACT FROM AUTHOR]

A new palladium(II) organometallic complex with liquid crystal properties was prepared and its electrical conduction was investigated in all specific mesophases. It was established that the electrical conduction is of ionic type. The negative differential electrical resistivity was evidenced. The effect is explained by the particular characteristics of the interactions between the charge carriers and the liquid crystal in electric field. A new method for determining the activation energy is proposed, based on the analysis of the ionic current dependency on voltage. The obtained results are of interest for the design of liquid crystal devices. [ABSTRACT FROM AUTHOR]

A new series of non-disc-like oxovanadium(iv) Schiff base complexes of the type [VO((4-CnH2n+1O)2salcn)], where n = 14, 16 or 18 and salcn is N,N'-bis-salicylidene-1,2-cyclohexadiamine, containing 4-substituted alkoxy tails in the side aromatic rings, have been synthesised and their mesogenic properties investigated. The compounds were characterised by FT-IR, 1H NMR, 13C NMR, UV-Vis and FAB mass spectrometry. The mesomorphic behaviour of the compounds was studied using polarised optical microscopy and differential scanning calorimetry. The molecular organisation in the mesophase was determined by X-ray diffraction. It was found that the ligands did not show mesogenic behaviour, but their complexes exhibited a thermally stable enantiotropic highly ordered three-dimensional plastic mesophase with a columnar structure in the extended temperature range 155-166°C. The clearing temperature of the complexes was found to be lower than in the structurally analogous copper complexes. A density functional theory study was carried out using DMol3 at BLYP/DNP level to obtain a stable optimised structure. A square pyramidal geometry for the vanadyl complexes has been proposed. [ABSTRACT FROM AUTHOR]

Abstract: A series of new mononuclear lanthanide(III)-salicylaldimine complexes of the type [Ln(LH)3(NO3)3] (Ln=La, Pr, Sm and Gd; LH= N-(2-hydroxyethyl)-4n-alkoxysalicylaldimine, n =14, 18) have been synthesized and characterized by FT-IR, 1H NMR, 13C NMR, UV–Vis, FAB-mass and magnetic susceptibility measurements. The ligand (LH) coordinate to lanthanide ions in zwitterionic form via the phenolic-oxygen with the proton shifted to the imine–nitrogen. The nitrato groups occurring in chelated bidentate fashion complete a nine-coordinate geometry. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) show that the ligands are monotropic and their complexes exhibit enantiotropic highly viscous smectic A (SmA) mesophase in the temperature range 60–185°C. A bilayer self organized assembly of the molecules in the mesophase are proposed on the basis of the small angle XRD study. The ligands are blue light emitters with a broad emission maxima at ∼447nm while the lanthanide complexes show intense emission in the visible range (∼465–679nm) at 350nm excitation. The samarium(III) complex, [Sm(LH)3(NO3)3] is distinct from the rest in emitting bright orange light (∼660nm, Φ =48%). The So–S1 excitation band being stronger than the direct f–f excitation in the samarium complex clearly suggests that the Schiff-base ligands efficiently sensitize the luminescence of Sm3+. DFT calculations have been performed using DMol3 program at BLYP/DNP level to obtain the stable electronic structure of the ligand and complex. [Copyright &y& Elsevier]

Abstract: A series of novel hemi-disclike four coordinated distorted square planar Zn(II) Schiff base complexes containing 4-substituted alkoxy chains on the side aromatic ring [Zn (4−C n H2 n +1O)2 salophen], n =14, 16, 18 and salophen= N,N′-4-methyl phenylene bis (salicylideneiminato), have been prepared and their mesogenic, photophysical properties were investigated. The phase behavior of these compounds were characterized by differential scanning calorimetry, polarized optical microscopy and variable temperature PXRD study. The ligands are non-mesogenic but the complexes exhibited an unprecedented 2D-hexagonal columnar mesophase (Colh) in the temperature 175–185°C range. In the mesophase (Colh), the molecules self assemble in a columnar stack in antiparallel fashion. All λ max of the UV–Vis absorption and photoluminescence band occurred at ca. 291–425 and 504–524nm, respectively. The ligands are non-emissive, but on coordination with Zn(II), the complexes show intense green emission at room temperature in dichloromethane solution (∼505nm, Φ =20%) as well as in solid (∼522nm, Φ =9%) at 360nm excitation. The DFT calculations were performed using Dmol3 program at BLYP/DNP level to obtain the stable electronic structure of the complex. A small LUMO-HOMO band gap (∼2.1eV), presumably suggests a rather strong electronic correlation among the molecules along the column. [Copyright &y& Elsevier]

Abstract: The syntheses of ferrocenylbiphenylisocyanide gold(I) thiophenolato complexes are described. The preparative route starts from ferrocenylphenylbromide and proceeds in six steps to yield the desired gold(I) complexes, (thiophenolato)gold{(4′-ferrocenyl[1,1′]biphenyl-4-yl)isocyanide} (11) and (thiophenolato)gold{(4′-ferrocenyl-3,5-dimethyl[1,1′]biphenyl-4-yl)isocyanide} (12) in good yields. The synthetic pathways were developed as a first step toward realizing the goal of preparing metallomesogens based on ferrocenyl-polyphenylenes coordinated to gold(I) thiophenolates, in which long chain alkoxy groups are substituted para to sulfur on the phenyl ring. The crystal structures of (chloro)gold{(4′-ferrocenyl[1,1′]biphenyl-4-yl)isocyanide} (9) and 12 are reported. Complex 9 crystallizes in the space group P21/c and 12 crystallizes in P21/n. Complexes 9 and 12 show short intermolecular Au–Au contacts of 3.3765(7)Å and 3.3334(3)Å, respectively. [Copyright &y& Elsevier]

A series of imidazole-containing rod-like Schiff's bases and their ionic copper(II) chelates with various lengths of the terminal alkyl chain containing 6, 8, 10, 12, 14 and 16 carbon atoms have been synthesised. The synthesised compounds were characterised by elemental analyses, 1H NMR, IR and UV-vis and mass spectroscopies. Thermotropic smectic C mesophases in the ligands and smectic A mesophases in the copper(II) complexes were identified using POM, DSC and small-angle XRD scattering methods. X-ray diffraction patterns of the prepared imidazole imines indicate to supramolecular self-assembled structures in the liquid crystal state, which are formed by means of intermolecular hydrogen bonds. It was established that both liquid crystal arrangement and supramolecular assemblies in ligands disappeared near 190°C, mainly regardless of the lengths of the terminal alkyl chains. Contrary, assembling of the copper(II) complexes into supramolecular bilayers occurs near 200°C, which causes their transition to a smectic A mesophase. [ABSTRACT FROM AUTHOR]

The monosubstituted ferrocene derivatives containing biphenyl group in mesogenic one, ω-[4-(4-methoxybiphenoxy carbonyl) phenoxycarbonyl] alkyl 4-ferrocenylbenzoate, have been synthesized by changing the carbon atoms number of the flexible spacer. The analogous compounds in which phenyl group was contained instead of biphenyl one have been prepared and reported previously. Their phase transition behavior has been studied by a differential scanning calorimeter and a polarizing microscope. The effect of an existence of the biphenyl group on their phase transition behavior and a comparison of the phase transition phenomena with that of ω-[4-(4-methoxyphenoxy carbonyl) phenoxycarbonyl] alkyl 4-ferrocenylbenzoate will be discussed. [ABSTRACT FROM AUTHOR]

The monosubstituted ferrocene derivatives, ω-[4-(4-methoxyphenoxycarbonyl) phenoxy]alkoxycarbonyl ferrocene, were synthesized in order to compare the liquid crystallinity to that of disubstituted ferrocene derivatives, 1,1'-bis[ω-[4-(4-methoxy-phenoxycarbonyl)phenoxy]alkoxycarbonyl]ferrocene. Some of the monosubstituted ferrocene derivatives containing relatively longer flexible spacer showed the liquid crystalline phase, nematic and/or smectic phases. The crystal structure of 2-[4-(4-methoxyphenoxycarbonyl)phenoxy]ethoxycarbonyl ferrocene was determined by X-ray diffraction method using a single crystal. The molecular structure revealed a bent structure that is almost a half of “Z” shaped molecular structure of 1,1'-bis[2-[4-(4-methoxyphenoxycarbonyl)phenoxy]ethoxycarbonyl]ferrocene. [ABSTRACT FROM AUTHOR]

Discotic metallomesogens were prepared by complexation of phenacylpyridine ligands with copper(II) and palladium(II) ions. Picoline derivatives with an alkoxy chain were prepared by the reaction of 5-hydroxy-2-methylpyridine with alkyl bromides. In a similar manner, methyl 3,4,5-trialkoxybenzoates were obtained from methyl 3,4,5-trihydroxybenzoates and alkyl bromides. 5-Alkoxy-2-methylpyridines were metallated with lithium diisopropylamine and reacted with methyl benzoates to give ligand compounds 1-3. Metal complexes Cu1-3 and Pd1-3 were prepared by complexation of the ligands with copper(II) acetate and palladium(II) acetate in tetrahydrofuran, respectively. The ligands did not form liquid crystals, but their metal complexes showed enantiotropic columnar hexagonal mesophases at room temperature. The metal complexes of phenacylpyridines showed a superior ability to self-assemble into ordered phases compared to their structural analogues, the salicylaldiminato complexes. [ABSTRACT FROM AUTHOR]

We have synthesised two novel series of octaphenoxyphthalocyaninato copper(II) complexes, (m-CnO)PcCu (n = 2-10: 2b-f), and bis(octaphenoxyphthalocyaninato)terbium(III) complexes, [(m-CnO)Pc]2Tb (n = 2-10: 3b-f), which were substituted by dodecyloxy chains at the p-positions in the phenoxy groups and various length of alkoxy chains at the m-positions in the phenoxy groups. Their mesomorphic properties were investigated by polarising microscopy, differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction techniques. The Cu complex (2b) and the Tb complexes (3b-d), having shorter chains at the m-positions in the phenoxy groups, exhibited a lamellocolumnar (ColL) mesophase. Moreover, it was revealed that the complexes (2 and 3) tend to change their mesophases of the order of Colh → ColL → Colr → Cub → Coltet with elongating the length of the alkoxy chains at the m-positions. [ABSTRACT FROM AUTHOR]

Cobalt(II) compounds [Co(C10C8C2-terpy)2](BF4)2 (1) and [Co(C12C10C2-terpy)2](BF4)2 (2) (CxCyCz-terpy = 4'-5'''-Alkyl-1'''-alkoxy-2,2':6',2''-terpyridine) with branched alkyl chains, based on a terpyridine frame, was synthesized. The cobalt(II) compounds 1 and 2 exhibit the spin transition between low-spin and high-spin with thermal hysteresis loop at the liquid crystal transition temperature (T1/2↑ = 275 K and T1/2↓ = 250 K for 1 and T1/2↑ = 307 K and T1/2↓ = 296 K for 2), and the spin transition is induced by crystal-mesophase transition. The bifunctional materials show synchronizing both spin transition and liquid crystal transition. [ABSTRACT FROM AUTHOR]