Synthesis and characterization of laterally substituted bis(alkoxybenzoyloxy)hydroquinones

A new series of laterally substituted bis(alkoxybenzoyloxy)hydroquinone compounds has been synthesized and their mesomorphic properties studied. A number of hydroquinone compounds were synthesized with terminal n -alkoxy chains ranging from n -butyloxy to n -decyloxy. Additionally, lateral substituents ranging from n -butyl to n -octyl were incorporated through esterification at the remaining unsubstituted phenolic oxygen atoms. By optimizing the combination of the end group and lateral moieties we were able to tailor the molecular structure to form different liquid crystalline phases.     

Ferroelectric properties of mixtures of a liquid crystalline polymer and its side-group mesogen

We present the results of our studies of the ferroelectric properties of mixtures of a high polarization, ferroelectric liquid crystalline copolymer and its side-group antecedent, a high polarization, low molecular weight, ferroelectric mesogen. These two materials are found to be completely miscible in all proportions. Spontaneous polarization values and electro-optical response times are found to be monotonic functions of the weight percentage of the mesogen in the mixture, while optical tilt angles do not exhibit such a monotonic dependence.     

Determination of excited state electric dipole moment of the isomeric fluorophenylisocyanates from solvatochromic shift measurements

The excited state electric dipole moments of three isomeric fluorophenylisocyanates are determined using the method of solvatochromic shift measurements recently suggested from our laboratory.     

Cyclitol-based metal-complexing agents. Effect of the relative orientation of oxygen atoms in the ionophoric ring on the cation-binding ability of myo-inositol-based crown ethers

myo-Inositol-derived crown ethers having varying relative orientations (1,3-diaxial, 1,2-diequatorial, and 1,2-axial-equatorial) of the oxygen atoms in the ionophoric ring were synthesized and the extent of their binding with picrates of alkali metals, ammonia, and silver were estimated. These crown ethers bind very well with potassium and silver picrates and show good to moderate binding toward lithium, sodium, cesium, and ammonium picrates. These myo-inositol-derived crown ethers exhibit very strong binding for silver, even though they do not have sulfur or nitrogen coordinating sites in them, which are known to have high affinity for silver. The ratio of binding constants for silver to other ions tested varies from 10(2) to 10(5). The ion selectivity and the strength of binding are dependent on the relative orientation of the oxygen atoms in the ionophoric ring as well as on the size of the macrocyclic ring.     

CONFORMATIONS OF DEOXYDODECANUCLEOTIDES WITH PYRIMIDINE (6-4) PYRIMIDONE PHOTOADDUCTS

Abstract— We have carried out molecular mechanical simulations of dodecanucleotide d(CGCGAAXYCGCG).d(CGCGX'Y'TTCGCG) with XY being CC, TC, TT and CT and X'Y'being their corresponding base paired dinucleotides on the complementary strand. Simulations were also carried out with the corresponding pyrimidine (6-4)-pyrimidone photoadducts incorporated in these dodecanucleotides. As in the case of the cyclobutane dimer incorporated dodecanucleotide structures (Rao et al., 1984), those regions of the DNA modified by6–4 pyrimidine adducts are found to undergo little conformational changes except in the dimer region. The conformational characteristics of the6–4 pyrimidine adduct incorporated structures seem to be influenced by the nature of the base at the 3' end of the dimer. Specifically, favorable hydrogen bonding interactions between the 5' end base and its preceding phosphate group are present in structures which have cytosine at the 3' end of the photodimer. The energetics of these structures relative to those without incorporated dimers have been discussed and the results have been analysed in the light of the currently prevalent ideas on the role of the6–4 photoadducts in mutagenesis in various organisms.     

Different interaction motifs of dipolar S=O...C=O contacts that associate diastereomers of 2,4(6)‐di‐O‐benzoyl‐6(4)‐O‐{[(1S)‐7,7‐dimethyl‐2‐oxobicyclo[2.2.1]heptan‐1‐ylmethyl]sulfonyl}‐myo‐inositol 1,3,5‐orthoacetate

Diastereomeric mixtures of 2,4(6)‐di‐O‐benzoyl‐6(4)‐O‐[(1S)‐10‐camphorsulfonyl]‐myo‐inositol 1,3,5‐orthoesters associate in their crystal structures via different geometries of S=O...C=O short contacts, depending upon the substitution. A comparison of the dimeric association in the orthoacetate and orthoformate (solvated) derivatives shows a sheared parallel motif of dipolar S=O...C=O contacts bridging the former, whereas perpendicular S=O...C=O contacts occur in the latter. The title compound, C₃₂H₃₄O₁₁S, is chiral, owing to the presence of the camphor moiety.     

Total synthesis of (−)-microcarpalide from d-mannitol

The total synthesis of the actin-targeting metabolite (−)-microcarpalide is described. Ring-closing metathesis of a dienic ester was used as the key step. d-Mannitol was used as the chiral pool material for the construction of the olefinic acid moiety as well as the olefinic alcohol moiety of the molecule.     

Liquid-crystalline behaviour of benzobisthiazole derivatives as a rigid rod polymer model

Novel materials with a new type of rigid core, namely benzobisthiazole, have been synthesized. The exhibition of liquid-crystallinity is found to be dependent upon the linkage between the rigid core and the alkyloxy phenyl terminal moieties. An interesting feature is the occurrence of tilted smectic phases (smectic C and smectic F) even though there is no significant central dipole moment transverse to the molecule.