Pyrene appended bile acid conjugates: Synthesis and a structure-gelation property study

A wide variety of novel compounds obtained by combining two types of known organogelators, viz., bile acid alkyl amides and pyrene alkanoic acids, were synthesized and screened for their gelation ability. The 3 alpha esters of 1-pyrene butyric acid (PBA) of alkylamides of deoxycholic acid (DCA) turned out to be effective in the gel formation with many organic solvents although the gelation has to be triggered by the addition of a charge transfer (CT) agent 2,4,7-trinitrofluorenone (TNF). The special feature of these molecules is that the organogelation is achieved only after derivatizing the acid moiety of the 1-pyrenealkanoic acids. Additionally, the gelation properties can be fine-tuned by inserting different functional groups at the bile acid side chain. The gels obtained are deep red in colour and optically transparent up to 2% w/v. The SEM studies of the obtained xerogels revealed bundled rod-like morphology without specialized branching.

Perfluoroalkyl bile esters: a new class of efficient gelators of organic and aqueous-organic media

A new class of fluorinated gelators derived from bile acids is reported. Perfluoroalkyl chains were attached to the bile acids through two different ester linkages and were synthesized following simple transformations. The gelation property of these derivatives is a function of the bile acid moiety, the spacer and the fluoroalkyl chain length. By varying these parameters, gels were obtained in aromatic hydrocarbons, DMSO and DMSO/DMF-H(2)O mixtures of different proportions. Several derivatives of deoxycholic and lithocholic acids were found to be efficient organogelators, while the reported bile-acid based organogelators are mostly derived from the cholic acid moiety. The efficient gelators among these compounds formed gels well below 1.0% (w/v) and hence they can be termed as supergelators. The mechanical properties of these gels could be modulated by changing either the bile acid moiety or by varying the length of the fluoroalkyl segment. The presence of CO(2)-philic perfluoroalkyl groups is also expected to enhance their solubility in supercritical CO(2) and hence these compounds are promising candidates for making aerogels.

Perfluoroalkyl bile esters: a new class of efficient gelators of organic and aqueous-organic media

A new class of fluorinated gelators derived from bile acids is reported. Perfluoroalkyl chains were attached to the bile acids through two different ester linkages and were synthesized following simple transformations. The gelation property of these derivatives is a function of the bile acid moiety, the spacer and the fluoroalkyl chain length. By varying these parameters, gels were obtained in aromatic hydrocarbons, DMSO and DMSO/DMF-H(2)O mixtures of different proportions. Several derivatives of deoxycholic and lithocholic acids were found to be efficient organogelators, while the reported bile-acid based organogelators are mostly derived from the cholic acid moiety. The efficient gelators among these compounds formed gels well below 1.0% (w/v) and hence they can be termed as supergelators. The mechanical properties of these gels could be modulated by changing either the bile acid moiety or by varying the length of the fluoroalkyl segment. The presence of CO(2)-philic perfluoroalkyl groups is also expected to enhance their solubility in supercritical CO(2) and hence these compounds are promising candidates for making aerogels.

Utilizing an ionic liquid for synthesizing a soft matter polymer ``gel'' electrolyte for high rate capability lithium-ion batteries

A cross-linked polymer ``gel'' electrolyte obtained from free radical polymerization of a vinyl monomer (acrylonitrile; AN) in a room temperature ionic liquid electrolyte (N,N-methyl butyl pyrrolidinium-bis (trifluoromethanesulphonyl)imide-lithium bis(trifluoromethanesulphonyl) imide;LiTFSI-[Py(1,4)-TFSI]) for application in high rate capability rechargeable lithium-ion batteries is discussed here. This is a novel alternative compared to the often employed approach of using a molecular liquid as the medium for performing the polymerization reaction. The polymer ``gel'' electrolytes (AN:Py(1,4)-TFSI = 0.16-0.18, w/w) showed remarkable compliable mechanical strength and higher thermal stability compared to LiTFSI-[Py(1,4)-TFSI]. Despite two orders increase in magnitude of viscosity of polymer ``gels'', the room temperature ionic conductivity of the ``gels'' (1.1 x 10(-3)-1.7 x 10(-3) Omega(-1) cm(-1)) were nearly identical to that of the ionic liquid (1.8 x 10(-3) Omega(-1) cm(-1)). The present ``gel'' electrolytes did not exhibit any ageing effects on ionic conductivity similar to the conventional polymer gel electrolytes (e.g. high molecular weight polymer + salt + high dielectric constant molecular solvent). The disorder (ionic liquid) to a relative order (cross-linked polymer electrolyte) transformation does not at all influence the concentration of conducting species. The polymer framework is still able to provide efficient pathways for fast ion transport. Unlike the ionic liquid which is impossible to assemble without a conventional separator in a cell, the polymer ``gel'' electrolyte could be conveniently assembled without a separator in a Li vertical bar lithium iron phosphate (LiFePO(4)) cell. Compared to the ionic liquid, the ``gel'' electrolyte showed exceptional cyclability and rate capability (current density: 35-760 mA g(-1) with LiFePO(4) electronically wired with carbon (amorphous or multiwalled nanotube [MWCNT]).

Antihyperlipidemic potential of Cedrus deodara extracts in monosodium glutamate induced obesity in neonatal rats

Objective: To study the antihyperlipidemic effect of Cedrus deodara (C. deodara) against monosodium glutamate (MSG) induced obesity in neonatal rats. Materials and Methods: The studies were carried out on newborn neonatal rats and were injected intraperitoneally with 2 mg/g of MSG on the 2(nd) and 4(th) postnatal days and 4 mg/g on 6(th), 8(th) and 10(th) postnatal days. Ethanolic extract (EE) and acetone extract (AE) of C. deodara was administered in a dose of 100 and 200 mg/kg, p.o./day at the age of 65 days. On day 60 of treatment, body weight, locomotor activity, body temperature, and various biochemical parameters like serum glucose, total cholesterol, triglyceride, and organs weights were recorded. Results: There was a significant reduction in body weight, organs and increased body temperature, locomotor activity after treatment with extracts. C. deodara decreased serum glucose, total cholesterol and triglyceride, low density lipoprotein (LDL) and very low density lipoprotein (VLDL) levels and increased high density lipoprotein (HDL) significantly has compared to MSG-control rats. Conclusion: C. deodara extracts exhibited antihyperlipidemic effect and it possesses anti-obesity properties in MSG induced obese rats.

Neuroprotective activity of Wedelia calendulacea on cerebral ischemia/reperfusion induced oxidative stress in rats

Objective: This study was undertaken to evaluate the neuroprotective activity of Wedelia calendulacea against cerebral ischemia/reperfusion induced oxidative stress in the rats. Materials and Methods: The global cerebral ischemia was induced in male albino Wistar rats by occluding the bilateral carotid arteries for 30 min followed by 1 h and 4 h reperfusion. At various times of reperfusion, the histopathological changes and the levels of malondialdehyde (MDA), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-s-transferase (GST), and hydrogen peroxide (H(2)O(2)) activity and brain water content were measured. Results: The ischemic changes were preceded by increase in concentration of MDA, hydrogen peroxide and followed by decreased GPx, GR, and GST activity. Treatment with W. calendulacea significantly attenuated ischemia-induced oxidative stress. W. calendulacea administration markedly reversed and restored to near normal level in the groups pre-treated with methanolic extract (250 and 500 mg/kg, given orally in single and double dose/day for 10 days) in dose-dependent way. Similarly, W. calendulacea reversed the brain water content in the ischemia reperfusion animals. The neurodegenaration also conformed by the histopathological changes in the cerebral-ischemic animals. Conclusion: The findings from the present investigation reveal that W. calendulacea protects neurons from global cerebral-ischemic injury in rat by attenuating oxidative stress.

Evidence of aggregation induced emission enhancement and keto-enol-tautomerism in a gallic acid derived salicylideneaniline gel

A novel salicylideneaniline type fluorescent organogelator based on a 3,4,5-(tri-dodecyloxy)benzoyl group immobilizes aromatic solvents. The resulting gels show enhancement in emission and thermochromic/non-photochromic behaviour during sol-to-gel transition.

Charge-transfer interaction mediated organogels from bile acid appended anthracenes: rheological and microscopic studies

In this article we present dual-component charge-transfer interaction (CT) induced organogel formation with bile acid anthracene conjugates as donors and 2,4,7-trinitrofluorenone (TNF) as the acceptor. The use of TNF (1) as a versatile electron acceptor in the formation of gels is demonstrated through the formation of gels with different steroidal groups on the anthracene moiety in a variety of solvents ranging from aromatic hydrocarbons to long chain alcohols. Thermal stability and variable temperature fluorescence experiments were performed on these CT gels. Dynamic rheological experiments conducted on these gels suggest that these are viscoelastic soft materials and with the gel strength can be modulated by varying the donor/acceptor ratios.

YGa1-xMnxO3: A novel purple inorganic pigment

A purple inorganic pigment, YGa1-xMnxO3 (0 < x <= 0.10), based on hexagonal YGaO3 is reported here. The metastable series of oxides were prepared by a sol-gel technique where the dried gels, obtained from aqueous solutions of metal nitrate-citric acid mixtures, were calcined for a short duration in a preheated furnace around 850 degrees C. The purple colour of the oxides arises from the specific trigonal bipyramidal ligand field around Mn-III in a YGaO3 host. Other hexagonal RGaO3 hosts for R = Lu, Tm and Ho substituted with Mn-III also produce similar purple coloured materials.

Organophotocatalysis in nanostructured soft gel materials as tunable reaction vessels: comparison with homogeneous and micellar solutions

Riboflavin tetraacetate-catalyzed aerobic photooxidation of 1-(4-methoxyphenyl)ethanol was investigated as a model reaction under blue visible light in different soft gel materials, aiming to establish their potential as reaction vessels for photochemical transformations. Three strategies involving different degrees of organization of the catalyst within the gel network were explored, and the results compared to those obtained in homogeneous and micellar solutions. In general, physical entrapment of both the catalyst and the substrate under optimized concentrations into several hydrogel matrices (including low-molecular-weight and biopolymer-based gels) allowed the photooxidation with conversions between 55 and 100% within 120 min (TOF similar to 0.045-0.08 min(-1); k(obs) similar to 0.011-0.028 min(-1)), albeit with first-order rates ca. 1-3-fold lower than in solution under comparable non-stirred conditions. Remarkably, the organogel made of a cyclohexane-based bisamide gelator in CH3CN not only prevented the photodegradation of the catalyst but also afforded full conversion in less than 60 min (TOF similar to 0.167 min(-1); k(obs) similar to 0.073 min(-1)) without the need of additional proton transfer mediators (e. g., thiourea) as it occurs in CH3CN solutions. In general, the gelators could be recycled without detriment to their gelation ability and reaction rates. Moreover, kinetics could be fine-tuned according to the characteristics of the gel media. For instance, entangled fibrillar networks with relatively high mechanical strength were usually associated with lower reaction rates, whereas wrinkled laminated morphologies seemed to favor the reaction. In addition, the kinetics results showed in most cases a good correlation with the aeration efficiency of the gel media.

Hybrid organogels and aerogels from co-assembly of structurally different low molecular weight gelators

The blending of perfluorinated bile ester derivatives with the gelator 2,3-didecyloxyanthracene (DDOA) yields a new class of hybrid organo- and aerogels displaying a combination of optical and mechanical properties that differ from those of pure gels. Indeed, the nanofibers constituting the hybrid organogels emit polarized blue light and display dichroic near-UV absorption via the achiral DDOA molecules, thanks to their association with a chiral bile ester. Moreover, the thermal stability and the mechanical yield stress of the mixed organogels in DMSO are enhanced for blends of DDOA with the deoxycholic gelator (DC11) having a C-11 chain, as compared to the pure components' gels. When the chain length of the ester is increased to C-13 (DC13) a novel compound for aerogel formation directly in scCO(2) is obtained under the studied conditions. A mixture of this compound with DDOA is also able to gelate scCO(2) leading to novel composite aerogel materials. As revealed by SAXS measurements, the hybrid and the pure DDOA and DC13 aerogels display cell parameters that are very similar. These SAXS experiments suggest that crystallographic conditions are very favorable for the growth of hybrid molecular arrangements in which DDOA and DC13 units could be interchanged. Specific molecular interactions between two components are not always a pre-requisite condition for the formation of a hybrid nanostructured material in which the components mutually induce properties.

Organogels from Dimeric Bile Acid Esters: In Situ Formation of Gold Nanoparticles

A new class of steroid dimers (bile acid derivatives) linked through ester functionalities were synthesized, which gelled various aromatic solvents. The organogels formed by the three dimeric ester molecules showed birefringent textures and fibrous nature by polarizing optical microscopy and scanning electron microscopy, respectively. A detailed rheological study was performed to estimate the mechanical strengths of two sets of organogels. In these systems, the storage modulus varied in the range of 0.8-3.5 X 10(4) at 1% w/v of the organogelators. The exponents of scaling of the storage modulus and yield stress of the two systems agreed well with those expected for viscoelastic soft colloidal gels with fibrillar flocs. The nanofibers in the organogel were utilized to engineer gold nanoparticles of different sizes and shapes and generate new gel-nanoparticle hybrid materials.

Induction of Supramolecular Chirality in the Self-Assemblies of Lipophilic Pyrimidine Derivatives by Choice of the Amino Acid-Based Chiral Spacer

A new family of supramolecular organogelators, based on chiral amino acid derivatives of 2,4,6-trichloro-pyrimidine-5-carbaldehyde, has been synthesized. L-alanine was incorporated as a spacer between the pyrimidine core and long hydrocarbon tails to compare the effect of chirality and hydrogen bonding to that of the achiral analogue. The role of aromatic moiety on the chiral spacer was also investigated by introducing L-phenyl alanine moieties. The presence of intermolecular hydrogen-bonding leading to the chiral self-assembly was probed by concentration-dependent FTIR and UV/Vis spectroscopies, in addition to circular dichroism (CD) studies. Temperature and concentration-dependent CD spectroscopy ascribed to the formation of -sheet-type H-bonded networks. The morphology and the arrangements of the molecules in the freeze-dried gels were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) techniques. Calculation of the length of each molecular system by energy minimization in its extended conformation and comparison with the small-angle XRD pattern reveals that this class of gelator molecules adopts a lamellar organization. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) indicate that the solid state phase behavior of these molecules is totally dependent on the choice of their amino acid spacers. Structure-induced aggregation properties based on the H-bonding motifs and the packing of the molecule in three dimensions leading to gelation was elucidated by rheological studies. However, viscoelasticity was shown to depend only marginally on the H-bonding interactions; rather it depends on the packing of the gelators to a greater extent.

Remarkable Regioisomer Control in the Hydrogel Formation from a Two-Component Mixture of Pyridine-End Oligo(p-phenylenevinylene)s and N-Decanoyl-L-alanine

N-Decanoyl-L-alanine (DA) was mixed with either colorless 4,4-bipyridine (BP) or various derivatives such as chromogenic oligo(p-phenylenevinylene) (OPV) functionalized with isomeric pyridine termini in specific molar ratios. This mixtures form salt-type gels in a water/ethanol (2:1, v/v) mixture. The gelation properties of these two-component mixtures could be modulated by variation of the position of the N atom of the end pyridyl groups in OPVs. The presence of acid-base interactions in the self-assembly of these two-component systems leading to gelation was probed in detail by using stoichiometry-dependent UV/Vis and FTIR spectroscopy. Furthermore, temperature-dependent UV/Vis and fluorescence spectroscopy clearly demonstrated a J-type aggregation mode of these gelator molecules during the sol-to-gel transition process. Morphological features and the arrangement of the molecules in the gels were examined by using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) techniques. Calculation of the length of each molecular system by energy minimization in its extended conformation and comparison with the XRD patterns revealed that this class of gelator molecules adopts lamellar organizations. Rheological properties of these two-component systems provided clear evidence that the flow behavior could be modulated by varying the acid/amine ratio. Polarized optical microscopy (POM), differential scanning calorimetry (DSC), and XRD results revealed that the solid-phase behavior of such two-component mixtures (acid/base=2:1) varied significantly upon changing the proton-acceptor part from BP to OPV. Interestingly, the XRD pattern of these acid/base mixtures after annealing at their associated isotropic temperature was significantly different from that of their xerogels.

Comparative Evaluation of Zoledronic Acid, Alfacalcidol and Propranolol in Pharmacological Correction of Experimental Osteoporosis

Propranolol, a beta-adrenergic receptor blocker, is presently considered to be a potential therapeutic intervention under investigation for its role in prevention and treatment of osteoporosis. However, no studies have compared the osteoprotective properties of propranolol with well accepted therapeu-tic interventions for the treatment of osteoporosis. To address this question, this study was designed to evaluate the bone protective effects of zoledronic acid, alfacalcidol and propranolol in an animal model of postmenopausal osteoporosis. Five days after ovariectomy, 36 ovariectomized (OVX) rats were divided in- to 6 equal groups, randomized to treatments zoledronic acid (100 μg/kg, intravenous single dose); alfacal-cidol (0.5 μg/kg, oral gauge daily); propranolol (0.1mg/kg, subcutaneously 5 days per week) for 12 weeks. Untreated OVX and sham OVX were used as controls. At the end of the study, rats were killed under anesthesia. For bone porosity evaluation, whole fourth lumbar vertebrae (LV4) were removed. LV4 were also used to measure bone mechanical propeties. Left femurs were used for bone histology. Propranolol showed a significant decrease in bone porosity in comparison to OVX control. Moreover, propranolol sig- nificantly improved bone mechanical properties and bone quality when compared with OVX control. The osteoprotective effect of propranolol was comparable with zoledronic acid and alfacalcidol. Based on this comparative study, the results strongly suggest that propranolol might be new therapeutic intervention for the management of postmenopausal osteoporosis in humans.