Polymorphic Phases of Supramolecular Liquid Crystal Complexes Laterally Substituted with Chlorine

New supramolecular complexes, based on H-bonding interactions between 4-(pyridin-4-yl) azo-(2-chlorophenyl) 4-alkoxybenzoates (Bn) and 4-[(4-(n-hexyloxy)phenylimino)methyl]benzoic acid (A6), were prepared and their thermal and mesomorphic properties investigated via differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FT-IR) in order to confirm their H-bonding interactions. The mesophase behavior of each mixture was examined by DSC and polarized optical microscopy (POM). According to the findings of the study, in all of the designed mixtures, the introduction of laterally polar chlorine atom to the supramolecular complexes produces polymorphic compounds possessing smectic A, smectic C and nematic mesophases, in addition, all products have low melting transitions. Thermal stabilities of the associated phases depend on the position and orientation of the lateral polar Cl− atom as well as the length of terminal flexible alkoxy chain. Comparisons were made between the present lateral Cl− complexes and previously investigated laterally-neat complexes in order to investigate the impact of the addition, nature and orientation of polar substituent on the mesomorphic behavior. The investigations revealed that, the polarity and mesomeric nature of inserted lateral substituent into the base component play an essential role in affecting their mesomorphic properties. Furthermore, for current complexes, induced polymorphic phases have been found by introducing the chlorine atom.

Fluorenonophane chlorobenzene solvate: molecular and crystal structures

The title compound, 19 H,79 H-3,5,9,11-tetraoxa-1,7(2,7)-difluorena-4,10(1,3)-dibenzenacyclododecaphane-19,79-dione (fluorenonophane), exists as a solvate with chlorobenzene, C42H28O6·C6H5Cl. The fluorenonophane contains two fluorenone fragments linked by two m-substituted benzene fragments. Some decrease in its macrocyclic cavity leads to a stacking interaction between the tricyclic fluorenone fragments. In the crystal, the fluorenonophane and chlorobenzene molecules are linked by weak C—H...π(ring) interactions and C—H...Cl hydrogen bonds. The Cl atom of chlorobenzene does not form a halogen bond. A Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyse the intermolecular contacts found in the crystal structure.

Crystal structure of hexakis(N,N-dimethylformamide-κO)iron(III) μ-chlorido-bis(trichloridocadmium)

The title compound, [Fe(C3H7NO)6][Cd2Cl7], crystallizes in the trigonal space group R\overline{3} and is assembled from discrete [Fe(DMF)6]3+ cations (DMF = N,N-dimethylformamide) and [Cd2Cl7]3− anions. In the cation, the iron(III) atom, located on a special position of \overline{3} site symmetry, is coordinated by six oxygen atoms from DMF ligands with all Fe—O distances being equal [2.0072 (16) Å]. A slight distortion of the octahedral environment of the metal comes from the cis O—Fe—O angles deviating from the ideal value of 90° [86.85 (7) and 93.16 (7)°] whilst all the trans angles are strictly 180°. The central Cl atom of the [Cd2Cl7]3− anion is also located on a special position of \overline{3} site symmetry and bridges two corner sharing, tetrahedrally coordinated CdII atoms. The two Cd atoms and the central Cl atom are colinear. The two sets of terminal chloride ligands on either side of the dumbbell-like anion are rotated relative to each other by 30°. In the crystal, the cations and anions, stacked one above the other along the c-axis direction, are held in place principally by electrostatic interactions. There are also C—H...Cl and C—H...O interactions, but these are rather weak. Of the six crystal structures reported to date for ionic salts of [Fe(DMF)6] n+ cations (n = 2, 3), five contain FeII ions. The title compound is the second example of a stable compound containing the [Fe(DMF)6]3+ cation. The existence of both [Fe(DMF)6]2+ and [Fe(DMF)6]3+ cations shows that the DMF ligand coordination sphere can accommodate changes in the charge and spin states of the metal centre.

Crystal structures of phosphine-supported (η5-cyclopentadienyl)molybdenum(II) propionyl complexes

Three cyclopentadienylmolybdenum(II) propionyl complexes featuring triarylphosphine ligands with different para substituents, namely, dicarbonyl(η5-cyclopentadienyl)propionyl(triphenylphosphane-κP)molybdenum(II), [Mo(C5H5)(C3H5O)(C18H15P)(CO)2], (1), dicarbonyl(η5-cyclopentadienyl)propionyl[tris(4-fluorophenyl)phosphane-κP]molybdenum(II), [Mo(C5H5)(C3H5O)(C18H12F3P)(CO)2], (2), and dicarbonyl(η5-cyclopentadienyl)propionyl[tris(4-methoxyphenyl)phosphane-κP]molybdenum(II) dichloromethane solvate, [Mo(C5H5)(C3H5O)(C21H21O3P)(CO)2]·CH2Cl2, (3), have been prepared from the corresponding ethyl complexes via phosphine-induced migratory insertion. These complexes exhibit four-legged piano-stool geometries with molecular structures quite similar to each other and to related acetyl complexes. The extended structures of the three complexes differ somewhat, with the para substituent of the triarylphosphine of (2) (fluoro) or (3) (methoxy) engaging in non-classical C—H...F or C—H...O hydrogen-bonding interactions. The structure of (3) exhibits modest disorder in the position of one Cl atom of the dichloromethane solvent, which was modeled with two sites showing approximately equivalent occupancies [0.532 (15) and 0.478 (15)].

Optomechanical switching of adsorption configurations of polar organic molecules by UV radiation pressure

Using photoemission spectroscopy (PES), we have systematically investigated the behavior of polar organic molecule, chloroaluminum phthalocyanine (ClAlPc), adsorbed in the Cl-down configuration on the Ag(111) substrate at low temperature − 195 °C under UV irradiation with a range of different photon fluxes. Judging from the evolution of photoemission spectral line shapes of molecular energy states, we discovered that the Cl atoms are so robustly anchored at Ag(111) that the impinging photons cannot flip the ClAlPc molecules, but instead they crouch them down due to radiation pressure; we observe that the phthalocyanine (Pc) lobes bend down to interact with Ag atoms on the substrate and induce charge transfer from them. As photon flux is increased, radiation pressure on the Pc plane initiates tunneling of the Cl atom through the molecular plane to turn the adsorption configuration of ClAlPc from Cl-down to an upheld Cl-up configuration, elucidating an optomechanical way of manipulating the dipole direction of polar molecules. Finally, work function measurements provide a distinct signature of the resulting upheld Cl-up configuration as it leads to a large increase in vacuum level (VL), ~ 0.4 eV higher than that of a typical flat-on Cl-up configuration driven by thermal annealing.

Synthesis of halogenated bicyclic molecules involving Prins cyclization from aldehydes and non-conjugated diene alcohol

The reactions of aldehydes and a non-conjugated alcohol, (E)-octa-3,7-dien-1-ol, in the presence of halogen-containing reagents afforded the corresponding halogenated bicyclic molecules in good yields. The optimization, scope and limitations of the reactions as well as scale-up reactions have been examined. Quantum chemical calculations helped clarify the microscopic mechanism of a key reaction process, the introduction of a Cl atom to a bicyclic carbocation.

Atmospheric Chlorine Reaction with N-Methyl-2-Pyrrolidinone (NMP)

Density functional theory (DFT) and Complete Basis Scale methods (CBS-QB3, G3B3) are used to investigate the reactivity, the mechanism, structure-reactivity relationship and the kinetics of N-methyl-2-pyrrolidinone (NMP) with Cl atom. To obtain rate constants of the reaction, the RRKM theory is employed at atmospheric pressure and temperature range 273–380 K. This study provides the rate coefficients and detailed H-abstraction mechanism for the reaction of Cl with NMP at high level of theoretical methods. The obtained rate constant ~ 0.92 x 10− 10 to 8.98 × 10− 10cm 3 molecule− 1s− 1 at 298 K agreed with those obtained previously for N,N-dimethyl formamide (DMF) and N,N-dimethyl acetamide (DMA). The study shows that the reaction mechanism of Cl with NMP goes favorably through an H-abstraction from N-methyl groups and adjacent CH2. The rates constants obtained for the three amides confirm our prediction regarding the structure-reactivity relationship where 1000/T.

Synthesis and Structure-Chirality Relationship Analysis of Steroidal Quinoxalines to Design and Develop New Chiral Drugs

Of the utmost importance of chirality in organic compounds and drugs, the present work reports structure-chirality relationship of three steroidal quinoxalines, which were synthesised by condensing diaminobenzenes with cholestenone. All the compounds were purified and characterised by varying analytical tools prior to their chiroptical analysis by circular dichroism (CD) technique. The substituent groups on quinoxalines contributed to determining the chiroptical properties of the compounds. The positive Cotton effects have been observed in the CD spectra of unsubstituted and methyl-substituted quinoxalines, which indicated their P helicity. Importantly, chloro-substituent on quinoxalines produced different CD behaviour, which can be attributed to the presence of three lone pairs of electrons on Cl atom. The present work provides guidelines for determining the chiral properties of steroidal quinoxalines, which can be useful to design and develop potential molecules of biological importance.