Study of the mesomorphism of benzoates and cinnamates

Two ester homologous series of carboxy (-COO-) and ethylene-carboxy (-CH=CH-COO-) mesogens, viz. α-4-[4’-n-alkoxybenzoyloxy] phenyl β-4’’-methoxy benzoyl ethylenes (1) and α-4-[4’-n-alkoxy cinnamoyloxy phenyl β-4’’-methoxy benzoyl ethylenes (2)] are discussed. Series (1) and (2) differ at their central linking group. Mesophase are observed at four and five number members in both homologue series. Enantiotropic nematogenic property is observed in both series (1) and (2), while some smectic property is exhibited in series (2). Thermal stability of nematic-isotropic in series (1) is relatively low as compared to (2), smectogenic property is totally absent in series (2). In phase diagram, solid-nematic, solid-isotropic, and nematic-isotropic curve follow zigzag path rising and falling. Transition temperatures are observed through hot stage polarizing microscope. Analytical data supports the structure of molecules. Threaded, Schlieren-type textures of homologues are observed through microscope.     

Preparation,characterisation, and crystal structure analysis of (2<Emphasis Type="Italic">E</Emphasis>,2′<Emphasis Type="Italic">E</Emphasis>)-3,3′-(1,4-phenylene)bis(1-(2-aminophenyl)prop-2-en-1-one

A novel bis-chalcone, (2E,2′E)-3,3′-(1,4-phenylene)bis(1-(2-aminophenyl)prop-2-en-1-one) is synthesized through a base catalyzed Claisen-Schmidt condensation reaction of terephthalaldehyde with 2-aminoacetophenone. Its structure (sp. gr. P\(\bar 1\), Z = 2) is determined from single crystal X-ray diffraction data. There are two independent centrosymmetric molecules with no significant differences in bond lengths and angles between them. The NMR, IR, HRMS, and UV spectral data of the prepared bis-chalcone are presented.     

Regioselective 5‐endo‐dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo‐substituted Indenes and Cyclopenta‐Fused Arenes

An efficient iodine‐mediated regioselective tandem approach for the synthesis of symmetric and asymmetric iodo‐substituted indenes and stereoselective cyclopenta [b]pyridine/thiophenes from easily accessible enediynes that proceeds by in situ formation of an iodonium intermediate followed by a regioselective 5‐endo‐dig cyclization has been described. The intramolecular electrophilic iodocyclization was selectively triggered by a distribution of electronic density along the alkyne bond. Subsequently, the iodo‐substituted indenes were diversified by employing palladium‐catalyzed cross‐coupling reactions and the coupled products were further confirmed by X‐ray crystallographic studies.     

A system of non-local parabolic PDE and application to option pricing

This article includes a proof of well posedness of an initial-boundary value problem involving a system of non-local parabolic partial differential equation (PDE), which naturally arises in the study of derivative pricing in a generalized market model, which is known as a semi-Markov modulated geometric Brownian motion (GBM) model We study the well posedness of the problem via a Volterra integral equation of second kind. A probabilistic approach, in particular the method of conditioning on stopping times is used for showing the uniqueness.     

Doubly Strapped Zwitterionic NIR-I and NIR-II Heptamethine Cyanine Dyes for Bioconjugation and Fluorescence Imaging

Heptamethine cyanine dyes enable deep tissue fluorescence imaging in the near infrared (NIR) window. Small molecule conjugates of the benchmark dye ZW800-1 have been tested in humans. However, long-term imaging protocols using ZW800-1 conjugates are limited by their instability, primarily because the chemically labile C4′-O-aryl linker is susceptible to cleavage by biological nucleophiles. Here, we report a modular synthetic method that produces novel doubly strapped zwitterionic heptamethine cyanine dyes, including a structural analogue of ZW800-1 , with greatly enhanced dye stability. NIR-I and NIR-II versions of these doubly strapped dyes can be conjugated to proteins, including monoclonal antibodies, without causing undesired fluorophore degradation or dye stacking on the protein surface. The fluorescent antibody conjugates show excellent tumor-targeting specificity in a xenograft mouse tumor model. The enhanced stability provided by doubly strapped molecular design will enable new classes of in vivo NIR fluorescence imaging experiments with possible translation to humans.     

Dynamic resolution of N-Boc-2-lithiopiperidine

Dynamic thermodynamic resolution of N-Boc-2-lithiopiperidine is possible using a chiral ligand; the two enantiomers of this organolithium can be resolved with selectivities of up to 85 : 15 from a selection of 26 chiral diamino-alkoxide ligands screened.     

Coordination chain polymeric assemblies of trivalent lanthanides with multidentate Schiff base synthetic, spectral investigation and thermal aspects

The coordination chain polymers of La(III), Ce(III), Pr(III), Nd(III) and Sm(III) with N,N’-di(o-thiophenyl)terephthalaldehydediimine have been prepared and characterized by elemental analysis, ¹H NMR, ¹³C NMR, magnetic measurements, infrared spectra, reflectance spectra and thermogravimetric analysis. A coordination number of seven around the metal ion is suggested. The thermal decompositions of the coordination polymers have been studied. The kinetic parameters have been calculated using Freeman-Carroll method. The thermodynamic activation parameters such as entropy (S*), preexponential factor (A), enthalpy (H*) and free energy of the decomposition (G*) have been evaluated.