Common Diol Research Articles

A Computational Study on the Antioxidant Activity of Certain Random Copolyesters Containing Bis(arylidene) Cycloalkanone Moiety in the Main Chain

A series of five random copolyesters was synthesized by polycondensation of different arylidene diols with curcumin as a common diol and a common diacid chloride in the ratio of 1:1:2, respectively. The five arylidene diols were synthesized by an acid-catalyzed Claisen condensation reaction. The repeating units present in these five random copolyesters and also the backbone was identified by FT-IR, 1H-NMR, and 13C-NMR spectroscopic techniques. The curcumin based copolyester exhibited good antioxidant activity, confirmed by various antioxidant activity determinations. Structural analysis such as HOMO and LUMO energies and the HOMO-LUMO energies gap of the molecule has been calculated using the B3LYP/6-311+G (d, p) level of theory. The antioxidant property of the molecule can be explained by the hydrogen atom transfer by theoretical study.

Total Synthesis of Stemarene and Betaerene Diterpenoids: Divergent Ring-Formation Strategy and Late-Stage C–H Functionalization

A unified protecting group-free approach to two stemarene and two betaerene diterpenoids through a bioinspired two-phase strategy has been developed, and three of them were obtained for the first t...

Cytotoxic Anti-Cancer Activity of Certain Thermotropic Liquid Crystalline Poly (Ester-Amides) Containing 2, 6-Bis (Benzylidene)Cyclohexanone Moiety in the Main Chain

Five thermotropic liquid crystalline poly(ester-amides) were synthesized by polycondensation method. The poly(ester-amides) were synthesized from varying dicarboxylic acids with a common diamine namely 4,4'-diaminobenzene and a common diol namely 2,6-bis(4-hydroxybenzylidene))cyclohexanone. For qualitative characterization, viscosity measurements and solubility data were used for these synthesized poly(ester-amides). The spectroscopic techniques such as FT-IR, 1H NMR, 13C NMR were performed to investigate the microstructural features of these synthesized poly(ester-amides). The thermal phase transition behavior of these poly(ester-amides) were studied by Differential Scanning Calorimetry (DSC) and Hot-stage Optical Polarized Microscopy (HOPM). The degree of crystallinity was assessed by X-ray diffraction (XRD) patterns. Scanning Electron Microscopic (SEM) technique was used to illustrate the morphology of these poly(ester-amides). The copolymer synthesized was subjected into in vitro anti-cancer activity studies against human breast cancer (MCF-7) cell line.
 Keywords: Bisbenzylidenecyclohexanone; poly(ester-amides); polycondensation; thermotropic liquid crystalline properties; cytotoxicity, anticancer.

Synthesis, Characterization and Photocrosslinkable Studies of Certain Thermotropic Liquid Crystalline Poly(ester-amides)

Five thermotropic liquid crystalline poly(ester-amides) were synthesized by polycondensation method using varying dicarboxylic acids with a common diamine namely 4,4-diaminodiphenyl and a common diol namely 2,6-bis(4-hydroxy-3-methoxybenzylidene)cyclohexanone (CHBV). The solubility data and viscosity measurements of these synthesized poly(ester-amides) were used for qualitative characterization. The spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR were performed for investigating micro structural features. By differential scanning calorimetry (DSC), the thermal phase transition behavior of these poly(ester-amides) was studied. Scanning electron microscopy (SEM) technique was used to investigate the morphology of these poly(ester-amides). By using UV-visible spectroscopic technique, the photocrosslinkability of these poly(ester-amides) were studied by irradiating these poly(ester-amides) under a 160 W medium pressure mercury lamp. SEM analysis of these UV irradiated poly(ester-amides) showed the changes in morphology. Thus, the poly(ester-amides) containing arylidene keto moiety in the main chain exhibited nematic mesophase and were photocrosslinked upon UV irradiation. X-ray diffraction (XRD) patterns of these poly(ester-amides) were taken to assess the degree of crystallinity.<div><br></div>

Switchable selectivity within a series of boronate esters for dynamic covalent exchange in nonaqueous solvents

The reversible condensation–hydrolysis reactions of boronic acids have proven to be a highly useful class of thermodynamically controlled dynamic covalent process, enabling the construction of sugar sensors, stimuli-responsive materials, and complex covalent architectures. Yet, the common diol or diphenol coupling partners tend to produce relatively unstable condensation products, exhibit oxidative sensitivity, or offer limited options for expanding structural diversity. To address these drawbacks, we explore a series of coupling partners including non-diol salicylate and salicylamide derivatives, in combination with two boronic acids. In nonaqueous solvents, the condensation–hydrolysis equilibria are sensitive to the nature and concentration of Lewis bases, with equilibrium constants that can be tuned across at least five orders of magnitude. Furthermore, differential responses to base concentration can be exploited to create a switchable dynamic covalent system in which a boronic acid can be cycled between expressing each of two condensation products with high fidelity, in response to a simple chemical stimulus.

Synthesis and characterization of photo-crosslinkable liquid crystalline copolyesters containing arylidene-keto and chalcone moieties

A series of six photo-crosslinkable thermotropic liquid crystalline copolyesters were prepared by polycondensation method at room temperature using tetra-n-butylammonium bromide as the phase transfer catalyst. The diacid chloride involved in this process was adipoyl chloride, the common diol (diol-1), also referred to as bischalcone diol, used was 3,3′-benzene-1,4-diylbis[1-(4-hydroxyphenyl)prop-2-en-1-one] and six different arylidene diols were involved as varying diols (diol-2), in the ratio 2:1:1. The common diol and the six arylidene diols were synthesized by the acid-catalyzed Claisen-Schmidt synthesis. The inherent viscosity ηinh of these six copolyesters was found between 0.35 and 0.45. The microstructure of the repeating unit present in the copolyester chain was confirmed by FT-IR, 1H–NMR and 13C–NMR spectroscopic techniques. Thermal transition temperatures, resolved from the DSC thermograms, were found to be well above room temperature. Optical polarizing microscopy was employed to establish the liquid crystalline property and all the polymers were found to have nematic phase. The photo-crosslinking behaviour of these copolyesters was studied in DMF solution at different time intervals. The copolyesters having methoxy group in them absorb UV-A rays (315–400 nm) for a longer duration, which promotes them to be good candidates for UV filters and sunscreens.

Asymmetric Synthesis of (+)-anti- and (-)-syn-Mefloquine Hydrochloride.

The asymmetric (er > 99:1) total synthesis of (+)-anti- and (-)-syn-mefloquine hydrochloride from a common intermediate is described. The Sharpless asymmetric dihydroxylation is the key asymmetric transformation used in the synthesis of this intermediate. It is carried out on an olefin that is accessed in three steps from commercially available materials, making the overall synthetic sequence very concise. The common diol intermediate derived from the Sharpless asymmetric dihydroxylation is converted into either a trans- or cis-epoxide, and these are subsequently converted to (+)-anti- and (-)-syn-mefloquine, respectively. X-ray crystallographic analysis of derivatives of (+)-anti- and (-)-syn-mefloquine is used to lay to rest a 40 year argument regarding the absolute stereochemistry of the mefloquines. A formal asymmetric (er > 99:1) synthesis of (+)-anti-mefloquine hydrochloride is also presented that uses a Sharpless asymmetric epoxidation as a key step.

Synthesis and characterization of certain photocrosslinkable thermotropic liquid crystalline random copolyesters containing arylidene moiety

A new series of 12 thermotropic liquid crystalline and photocrosslinkable random copolyesters were synthesized from terephthalic acid, isophthalic acid and 4,4'-oxybis(benzoic acid) with four different arylidene diols and a common diol 1,2-bis(4-hydroxybenzoyloxy)ethane by direct polycondensation with diphenylchlorophosphate. The resulting polymers had inherent viscosities in the range 1.20–1.74 dl/g. Their structural features were investigated by Fourier transform infrared (FTIR), 1H, and 13C nuclear magnetic resonance (NMR) spectroscopy. The thermal behaviour of the copolyesters was investigated with differential scanning calorimetry and hot stage optical polarized microscopy. Our investigation on the effect of monomer structure on liquid crystalline behaviour shows that the copolymers containing bis(benzylidene)cycloalkanone exhibited higher melting and isotropization temperatures and extended liquid crystalline range. All of the copolymers showed some degree of crystallinity as evidenced by wide-angle X-ray diffraction and scanning electron microscopy. The photocrosslinkability of these polymers was established with UV irradiation/UV spectroscopy and scanning electron microscopy.

Synthesis, Characterization and Ultrasonic Determination of Certain Copolyesters Containing Bis (Arylidene) Acetone Moiety in the Main Chain

Six copolyesters were prepared from bis(4-hydroxybenzylidene)acetone (HBAC) and bis(4-hydroxy-3- methoxybenzylidene)acetone (MBAC) (as varying diol, diol-1) with adipoyl chloride, azelaic acid dichloride and sebacoyl chloride and 4-(4-nitrophenylazo)resorcinol (as a common diol, diol-2) by phase transfer catalysed condensation. These copolyesters were characterized by viscometry and spectrometry. DSC thermograms were recorded for all the copolyesters to determine the glass transition temperatures (T g ). The acoustical parameters of all the copolyesters were calculated from the measured ultrasonic velocity (U) and density (ρ) values at different temperatures in N,N-dimethylacetamide (DMAc) solution. The glass transition temperature values were determined from the trend in few calculated acoustical parameters with temperature and compared with those obtained from thermograms taken using differential scanning calorimetry. The molecular interactions at T g in the copolyester solutions have been investigated from these studies.

Synthesis of Aza‐, Oxa‐, and Thiabicyclo[3.1.0]hexane Heterocycles from a Common Synthetic Intermediate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Aza-, Oxa-, and Thiabicyclo[3.1.0]hexane Heterocycles from a Common Synthetic Intermediate

[reaction: see text] An efficient and stereospecific approach to the synthesis of structurally constrained aza-, oxa-, and thiabicyclo[3.1.0]hexane heterocycles has been achieved through application of the intramolecular cyclopropanation reaction of diazoacetates. The various constrained heterocycles (X = N, O, or S) are conveniently prepared from a common diol intermediate accessible from readily available cinnamyl alcohols. Application of the methodology to the synthesis of conformationally constrained oxazolidinone antibacterials is also discussed.