Discotic liquid crystals of transition metal complexes: 28. Temperature-dependent electronic spectra and X-ray structural analysis of discotic liquid crystalline bis(octakisdodecyloxyphthalocyaninato)lutetium(III) complex

Synthesis and liquid crystal behavior of bis[3,4,12,13,21,22,30,31-octa(dodecylthio)-2,3-naphthalocyaninato] rare earth complexes

A series of novel bis[3,4,12,13,21,22,30,31-octa(dodecylthio)-2,3-naphthalocyaninato] rare earth(III) complexes M [ Nc ( SC 12 H 25)8]2( M = Nd , Eu , Gd , Tb , Y , Ho , Er ) have been prepared by tetramerization of 2,3-bis(dodecylthio)-6,7-dicyanonaphthalene with M ( acac )3·n H 2 O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These sandwich double-decker complexes were characterized by elemental analysis and various spectroscopic methods including UV-vis, near IR, IR, and mass spectroscopies. Their liquid crystal behavior was studied by polarized optical microscope (POM), differential scanning calorimeter (DSC), and X-ray diffraction. These alkylthio-substituted bis(2,3-naphthalocyaninato) rare earth complexes yield a hexagonal columnar liquid crystal whose stable temperature range is between 42 and 243°C. The stable temperature domain of the mesophase shows a trend to be dependent on the central rare earth ionic size. In contrast, the molecular packing of these complexes as revealed by X-ray diffraction was found to be almost independent of the ionic size of the central rare earth.

Synthesis of organo-soluble metallophthalocyanines bearing electron-withdrawing substituents

The syntheses of organo-soluble metallophthalocyanines having sulfo- and sulfonamido- electron-withdrawing substituents are reported. The simple cation exchange of the readily available tetrasodium salt of metallo-sulfophthalocyanines 1( M = Ni , Co , Fe , Cr ) by alkylammonium salts afforded the sulfophthalocyanines 2 and 3 in good yields. Complexes 2 featuring two long C 18 alkyl chains are only soluble in organic solvents while tetrabutylammonium counter ions exhibit a dual solubility in both organic solvents and water for compounds 3. The tetrasulfonamidophthalocyanine complexes 5–7 with four C8, four C18 or eight C8 alkyl chains have been obtained after chlorination of the sulfophthalocyanines 1 leading to the chlorosulfonyl derivatives 4, followed by reaction with various substituted amines. The synthesis of the chromium precursors with tetrasulfo and tetrachlorosulfonyl substituents is also described.

Synthesis and liquid crystal behavior of tris[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth complexes

A series of tris[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth(III) complexes M 2[ Pc ( OC 8 H 17)8]3 [ M = Eu , Gd , Y , Lu ] has been prepared by the reaction of corresponding bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth complexes with M ( acac )3·n H 2 O in refluxing 1,2,4-trichlorobenzene. These liquid crystalline sandwich, triple-decker complexes were characterized by elemental analysis and various spectroscopic methods including 1 H NMR, UV-vis, IR and mass spectroscopies. Their liquid crystal phase transition behavior was studied by Polarized Optical Microscope, Differential Scanning Calorimeter and X-ray diffraction. The complexes, with octyloxy attached as side chains, showed rectangular columnar liquid crystal phases in a liquid crystal temperature range between 83 and 305°C. In addition to the rare earth contraction, both the transition temperature and the wide temperature range of the mesophase show a slight but obvious trend to decrease, respectively, in the same order. In contrast, the molecular packing of these complexes as revealed by X-ray diffraction was found to be almost independent of the ionic size of the central rare earth.

Liquid Crystal Behaviour of 2,3,9,10,16,17,23,24-Octakis(octyloxy)phthalocyanine-containing Gadolinium Sandwich Complexes

A series of six liquid crystalline phthalocyaninato gadolinium sandwich complexes that include two double-decker species Gd(Pc)[Pc(OC8H17)8] (1) [Pc(OC8H17)8 = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] and Gd[Pc(OC8H17)8]2 (2) and four triple-decker species (Pc)Gd(Pc)Gd[Pc(OC8H17)8] (3), (Pc)Gd[Pc(OC8H17)8]Gd(Pc) (4), (Pc)Gd[Pc(OC8H17)8]Gd[Pc(OC8H17)8] (5), and Gd2[Pc(OC8H17)8]3 (6) have been designed and their liquid crystal phase transition behaviour has been systematically studied by differential scanning calorimetry, X-ray diffraction, and polarized optical microscopy. The clearing point seems to show a dependence on the molecular structure of the sandwich compounds, increasing from double-decker to triple-decker along with an increase in the number of substituted 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine ligand both in the double- and triple-decker compounds. The liquid crystalline mesophases display a hexaganol columnar and/or rectangular columnar molecular arrangement depending on the molecular structure of sandwiches, which suggests the cooperation of the π–π stacking and the influence of octyloxy side chains on the liquid crystal formation. In addition, the textures of this series of double- and triple-decker sandwich complexes formed in the liquid crystalline mesophase exhibit high stability even after the mesophases of the compounds are heated to a clear isotropic liquid and cooled to room temperature, which is expected to be an efficient method to construct molecular electronic devices.

A new double-decker phthalocyanine mesogen

The valence state and the mesomorphic behaviour of a new cerium phthalocyanine double-decker complex bearing thioalkyl substituents are described and spectroscopic studies have revealed that the metal center in this lanthanide double-decker complex is tetravalent making the whole molecule neutral.

Upward Temperature Shift of the Intrinsic Phase Lag of the Magnetization of Bis(phthalocyaninato)terbium by Ligand Oxidation Creating an S = 1/2 Spin

An alternating-current (ac) magnetic susceptibility measurement for the [(Pc)(2)Tb(III)](0) complex (Pc = phthalocyaninato) has shown that ligand oxidation of the anionic [(Pc)(2)Tb(III)](-) complex gives rise to a significant upward shift of the temperature range where the magnetization response shows a phase lag behind the time-varying external magnetic field. The peaks of the out-of-phase component of the ac susceptibility of the pi-radical [(Pc)(2)Tb(III)](0) were observed at 50, 43, and 36 K with ac magnetic fields of 10(3), 10(2), and 10 Hz, respectively, which were more than 10 K higher than the corresponding values of the anionic complex with a closed-shell pi-system. The ac susceptibility measurements on the complex with octa(dodecoxy)-substituted Pc ligand, which is readily dilutable in diamagnetic media, proved that the significant rise of the temperatures occurs as an intrinsic single-molecular property of the complex possessing both J = 6 and S = (1)/(2) systems, and is not due to long-range magnetic order or interactions between adjacent unpaired pi-electrons.