Synthesis, spectroscopic, electrochemical and photophysical properties of high band gap polymers for potential applications in semi-transparent solar cells.

BACKGROUND: The design of new polymers able to filter the electromagnetic spectrum and absorb distinctly in the UV and high-energy part of visible spectrum is crucial for the development of semi-transparent solar cells. Herein, we report on the synthesis and spectroscopic, electrochemical, and photophysical characteristics of three new polymers, namely (i) Poly(triamterene-co-terephthalate), (ii) Poly[triamterene-co- 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-p,p'-disulfonamide], and (iii) Poly(5-hydroxyindole-2-carboxylate) that might show promise as materials for semi-transparent solar cells. RESULTS: The energy band gap, refractive index, dielectric constant, and optical conductivity of the electron donor polymer, poly(triamterene-co-terephthalate), were determined to be 2.92 eV, 1.56, 2.44 and 2.43 × 104 S cm-1, respectively. The synthesized electron acceptor polymers showed a relatively high refractive index, dielectric constant, and optical conductivity. The presence of a direct allowed transition was confirmed between intermolecular energy bands of the polymers. CONCLUSIONS: The polymers showed relatively high energy gap and deep HOMO levels, making them strong absorbers of photons in the UV region and high energy part of the visible region. The synthesized donor and acceptors performed well relative to P3HT and fullerenes due to the close match of the HOMO and LUMO levels. With further development, the polymers could be viable for use as the active layers of semi-transparent solar cells.

A study on the spectroscopic, energy band, and optoelectronic properties of α,ω-dihexylsexithiophene/tris(8-hydroxyquinolinate) gallium blends; DH6T/Gaq3 composite system.

In this work the optical response, spectroscopic behaviour, and optoelectronic properties of solution and solid state composite systems based on α,ω-dihexylsexithiophene/tris(8-hydroxyquinolinate) gallium (DH6T/Gaq3) are studied upon the incorporation of different molar percentages of Gaq3. UV-vis, PL, FTIR spectrophotometers and SEM technique were utilized to perform the investigations. The results showed a reduced energy band (Eg) (from 2.33eV to 1.83eV) and a broadened absorption spectrum for the blend system when 29.8% molar of Gaq3 was incorporated. These were attributed to the enhanced intermolecular interactions that are brought about by the increased strength of π-π overlap between the molecular moieties. A mathematical formula was developed to interpret the non-monotonic change occurred in Eg, while numerical calculations have been made to assign the type and nature of the electronic transitions governing the spectroscopic behaviour of the system. The results were elaborated and comprehensively discussed in terms of the exciton generation, energy band theory, molecular interactions, and spatial geometry.

Gastroprotective effect of desmosdumotin C isolated from Mitrella kentii against ethanol-induced gastric mucosal hemorrhage in rats: possible involvement of glutathione, heat-shock protein-70, sulfhydryl compounds, nitric oxide, and anti-Helicobacter pylori activity.

BACKGROUND: Mitrella kentii (M. kentii) (Bl.) Miq, is a tree-climbing liana that belongs to the family Annonaceae. The plant is rich with isoquinoline alkaloids, terpenylated dihydrochalcones and benzoic acids and has been reported to possess anti-inflammatory activity. The purpose of this study is to assess the gastroprotective effects of desmosdumotin C (DES), a new isolated bioactive compound from M. kentii, on gastric ulcer models in rats. METHODS: DES was isolated from the bark of M. kentii. Experimental rats were orally pretreated with 5, 10 and 20 mg/kg of the isolated compound and were subsequently subjected to absolute ethanol-induced acute gastric ulcer. Gross evaluation, mucus content, gastric acidity and histological gastric lesions were assessed in vivo. The effects of DES on the anti-oxidant system, non-protein sulfhydryl (NP-SH) content, nitric oxide (NO)level, cyclooxygenase-2 (COX-2) enzyme activity, bcl-2-associated X (Bax) protein expression and Helicabacter pylori (H pylori) were also investigated. RESULTS: DES pre-treatment at the administered doses significantly attenuated ethanol-induced gastric ulcer; this was observed by decreased gastric ulcer area, reduced or absence of edema and leucocytes infiltration compared to the ulcer control group. It was found that DES maintained glutathione (GSH) level, decreased malondialdehyde (MDA) level, increased NP-SH content and NO level and inhibited COX-2 activity. The compound up regulated heat shock protein-70 (HSP-70) and down regulated Bax protein expression in the ulcerated tissue. DES showed interesting anti-H pylori effects. The efficacy of DES was accomplished safely without any signs of toxicity. CONCLUSIONS: The current study reveals that DES demonstrated gastroprotective effects which could be attributed to its antioxidant effect, activation of HSP-70 protein, intervention with COX-2 inflammatory pathway and potent anti H pylori effect.

17-Deoxoestrone [estra-1,3,5(10)-trien-3-ol]-methanol (3/1).

Three independent mol-ecules of the title estrone derivative and a mol-ecule of methanol comprise the asymmetric unit of the title compound [systematic name: 13-methyl-6,7,8,9,11,12,13,14,15,16-deca-hydro-cyclo-penta-[a]phenanthren-3-ol-meth-an-ol (3/1)], 3C(18)H(24)O·CH(3)OH. Two of the estrone mol-ecules exhibit 50:50 disorder (one displays whole-mol-ecule disorder and the other partial disorder in the fused five- and six-membered rings) so that five (partial) mol-ecular conformations are discernable. The conformation of the six-membered ring abutting the aromatic ring is close to a half-chair in all five components. The conformation of the six-membered ring fused to the five-membered ring is based on a chair with varying degrees of distortion ranging from minor to significant. Two distinct conformations are found for the five-membered ring: in four mol-ecules, the five-membered ring is twisted about the bond linking it to the six-membered ring, and in the other, the five-membered ring is an envelope with the quaternary C atom being the flap atom. The crystal packing features O-H⋯O hydrogen bonding whereby the four mol-ecules comprising the asymmetric unit are linked into a supra-molecular chain along the b axis.

3ß-Acet-oxy-6-hy-droxy-imino-cholestane.

Two independent mol-ecules comprise the asymmetric unit of the title cholestane derivative, C(29)H(49)NO(3) {systematic name: (3S,8S,9S,10R,13R,14S,17R)-17-[(1R)-1,5-dimethyl-hex-yl]-6-hy-droxy-imino-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetra-deca-hydro-1H-cyclo-penta-[a]phenanthren-3-yl ace-tate}. The major differences between the mol-ecules relate to the relative orientations of the terminal acetyl [C-C-O-C torsion angles = -158.8 (3) and -81.7 (3)°] and alkyl groups [C-C-C-C = 168.9 (3) and 65.8 (4)°]. In the crystal, the independent mol-ecules associate via pairs of O-H⋯N hydrogen bonds, forming dimeric aggregates. Supra-molecular layers in the ab plane are mediated by C-H⋯O inter-actions.

Chisomicines A-C, limonoids from Chisocheton ceramicus.

Three new limonoids, chisomicines A-C (1-3), have been isolated from the bark of Chisocheton ceramicus. Their structures were determined by 2D NMR, CD spectroscopic methods, and X-ray analysis. Chisomicine A (1) exhibited NO production inhibitory activity in J774.1 cells stimulated by LPS dose-dependently at high cell viability.

Boronate derivatives of functionally diverse catechols: stability studies.

Benzeneboronate of catecholic carboxyl methyl esters, N-acetyldopamine, coumarin and catechol estrogens were prepared as crystalline derivatives in high yield. Related catechol compounds with extra polar functional group(s) (OH, NH2) do not form or only partially form unstable cyclic boronate derivatives.

5,22-Stigmastadien-3ß-yl p-toluene-sulfonate.

The asymmetric unit of the title compound {systematic name: (3S,8S,9S,10R,13R,14S,17R)-17-[(E,2R,5S)-5-ethyl-6-methyl-hept-3-en-2-yl]-10,13-dimethyl-2,3,4,7,8,9,11,12,14,15,16,17-dodeca-hydro-1H-cyclo-penta-[a]phenanthren-3-yl p-toluene-sulfonate}, C(36)H(54)O(3)S, comprises two independent mol-ecules that differ significantly in terms of the relative orientations of the peripheral groups; the conformation about the C=C bond of the side chain is E. In the crystal, mol-ecules associate into linear supra-molecular chains aligned along the a axis via C-H⋯O inter-actions.

3-Methyl-5α-cholest-2-ene.

In the title cholestane derivative, C(28)H(48) [systematic name: (1S,2S,7R,10R,11R,14R,15R)-2,5,10,15-tetra-methyl-14-[(2R)-6-methyl-heptan-2-yl]tetra-cyclo-[8.7.0.0(2,7).0(11,15)]hepta-dec-4-ene], the cyclo-hexene ring adopts a half-chair conformation. The parent 5α-cholest-2-ene and the equivalent fragment of the title compound are almost superimposable (r.m.s. deviation = 0.033 Å).

(8S,9R,10S,11S,13S,14S,16S,17R)-4,4-Dichloro-16ß-methyl-3,20-dioxo-17,21-bis-(propano-yloxy)-5ß,8ß-epoxy-pregna-1,9-diene.

The title compound, C(28)H(34)Cl(2)O(7), is a derivative of the glucocorticoid steroid beclomethasone dipropionate. It features an expoxide linkage [angle at oxygen = 96.6 (2)°]. The dichlorocyclohexenone ring adopts an envelope conformation, with the C atom bearing the two Cl substituents representing the flap. The dichloro-methyl C atom deviates by 0.471 (4) Šfrom the plane defined by the other five atoms, whose maximum r.m.s. deviation is 0.04 Å.

(20S)-22-Acetoxymethyl-6ß-meth-oxy-3α,5-dihydro-3'H-cyclo-propa[3α,5]-5α-pregnane.

In the title steroid derivative, C(25)H(40)O(3), the fused cyclo-propane unit that corresponds to a part of the A ring has a ß-configuration and the associated cyclo-pentane ring an envelope-shaped conformation.

3-Iodo-8ß,9α,14α-estra-1,3,5(10)-trien-17-one.

In the title compound, C(18)H(21)IO, the cyclo-hexane ring adopts a chair conformation, whereas the cyclo-pentane ring and the ten-membered tetra-line portions each adopt an envelope conformation. For the five-membered ring, the methine C atom deviates by 0.638 (4) Š(r.m.s. of the four other atoms is 0.005 Å) and for the ten-membered ring, the methine C atom constituting the flap deviates by 0.671 (3) Š(r.m.s. of the other nine atoms is 0.066 Å).

9α-Bromo analog of beclometasone dipropionate monohydrate.

In the crystal structure of (8S,9R,10S,11S,13S,14S,16S,17R)-9α-bromo-11-hydr-oxy-10,13,16-trimethyl-3-oxo-17-[2-(propion-yloxy)acet-yl]-6,7,8,9,10,11,12,13,14,15,16,17-dodeca-hydro-3H-cyclo-penta-[a]phenanthren-17-yl propionate monohydrate, C(28)H(37)BrO(7)·H(2)O, which has a 9α-Br atom in place of the 9α-Cl atom of monohydrated beclometasone dipropionate, one six-membered ring is planar (r.m.s. deviation = 0.02 Å) owing to its 1,4-diene-3-one composition, whereas the two other six-membered rings each have a chair conformation. The organic mol-ecule and water mol-ecules engage in hydrogen-bonding inter-actions, generating a helical chain running along the c axis of the ortho-rhom-bic unit cell.

2-Bromo-beclometasone dipropionate.

In the crystal structure of 2-bromo-beclometasone dipropionate [systematic name: (8S,9R,10S,11S,13S,14S,16S,17R)-2-bromo-9α-chloro-11-hydr-oxy-10,13,16-trimethyl-3-oxo-17-[2-(propion-yloxy)acet-yl]-6,7,8,9,10,11,12,13,14,15,16,17-dodeca-hydro-3H-cyclo-penta-[a]phenanthren-17-yl propionate], C(28)H(36)BrClO(7), the six-membered ring with the 1,4-diene-3-one composition is planar (r.m.s. deviations = 0.03 and 0.04 Šfor the two independent mol-ecules), whereas the remaining six-membered rings have chair conformations. Each of the independent mol-ecules self-associates via O-H⋯O(propionate) hydrogen bonding, generating a supra-molecular chain running along the b axis. The crystal is twinned, with the monoclinic unit cell emulating an orthorhomic crystal system; the major twin component constitutes approximately 60%.

(20R,24R,25S)-3α,7α,12α,27-Tetra-acet-oxy-24,26-ep-oxy-5ß-cholestane.

In the title anhydro-scymnol tetra-acetate, C(35)H(54)O(9), the fused chair conformation of the cyclo-hexane A/B ring junction is cis with a 5ß-H configuration. The compound has a trimethyl-ene oxide ring at position 24,26 and four acetate groups at the 3α,7α,12α,27 positions.

(20R)-24-Bromo-5ß-cholane.

In the title compound (5S,8R,9R,10R,13S,14S,17R,20R)-24-bromo-5ß-cholane, C(24)H(41)Br, the fused-chair conformation of the cyclo-hexane A/B ring junction is cis with a 5ß-H configuration.

(20S)-22-Iodo-methyl-6ß-meth-oxy-3α,5-dihydro-3'H-cyclo-propa[3α,5]-5α-pregnane.

In the title steroid derivative, C(23)H(37)IO, the fused cyclo-propane unit that comprises part of the A ring has a ß-configuration, and the associated cyclo-pentane ring has an envelope conformation.