Studies on the growth,structural, optical,SHG and thermal properties of γ-glycine single crystal: An organic nonlinear optical crystal

Single crystals of the organic nonlinear optical material γ-glycine have been grown in the presence of Zinc sulphate by slow evaporation technique at ambient temperature for the first time. Bulk growth of γ-glycine single crystals was grown by Top-seeded solution growth method. The γ-phase of glycine was confirmed by powder X-ray diffraction and the FTIR analysis. Elemental analysis CHN was performed to confirm the non-inclusion of zinc sulphate species into the solution. Inductively coupled plasma optical emission spectrometry study (ICP-OES) was employed to quantify the concentration of Zinc element in the grown γ-glycine single crystals. The optical transmission was ascertained from UV–Vis–NIR spectrum. The optical band gap was estimated for γ-glycine single crystal using UV–Vis–NIR study. Differential scanning calorimetry analysis was employed to explore information about thermal stability, phase transition and melting point of the grown crystal. The second harmonic generation relative efficiency was measured by Kurtz and Perry powder technique.     

Effect of ammonium acetate addition on crystal growth,spectral, thermal and optical properties of glycine single crystals

Gamma glycine single crystal is a potential organic nonlinear optical (NLO) material. It has been grown from a mixture of aqueous solutions of glycine and ammonium acetate by slow evaporation solution growth technique at room temperature for the first time. Powder X-ray diffraction studies are carried out and the results are compared. CHN analysis confirms the non-inclusion of ammonium acetate species in to the solution. FTIR studies are performed to identify the presence of various functional groups in the grown crystal. Differential scanning calorimetry analysis (DSC) was carried out to study the thermal stability and phase transition of the grown crystal. The optical analysis shows that UV cut-off of γ-glycine is at 190 nm and it has a wide transparency window. The second harmonic generation relative efficiency of the grown crystals was observed to be 1.72 times that of potassium dihydrogen orthophosphate (KDP).     

A direct entry to the 1-methoxyindole skeleton and to the corresponding indoles by a novel rearrangement: general syntheses of substituted 1-methoxyindoles

A short and efficient route to 1-methoxyindoles via a novel rearrangement is disclosed. This route involves only three steps from commercially available nitro compounds. The methodology is also generalized with a variety of examples to afford a series of 2-substituted-1-methoxyindoles possessing an electron-withdrawing group at position 3. In addition, a 1-methoxyindole compound 10 was converted to the corresponding indole 11 under mild conditions thereby constituting a new synthesis of substituted indoles.     

An efficient total synthesis of 9-methoxycarbazole-3-carbaldehyde based on a novel methodology for the preparation of methoxyindoles

A direct synthesis of naturally occurring 9-methoxycarbazole-3-carbaldehyde 1, based on our methodology for the synthesis of 1-methoxyindoles, is reported. A novel benzannulation strategy was employed using ring closing metathesis as the key step in this total synthesis. The synthesis of the natural product 1 has been achieved in seven steps in 14% overall yield from commercial materials and in only four steps from a methoxyindole compound obtained using the new methodology.     

Efficient synthesis of 19-31 membered macrocyclic tetralactones via ring closing metathesis in ionic liquids

The ring closing metathesis reaction in the presence of Grubbs catalyst was demonstrated using several ionic liquids to synthesize a range of macrocyclic tetralactones having ring size of 19 to 31 membered with different spacers. The ionic liquid [mmim][PF₆] was found to be an excellent solvent and the recovery of the catalyst was demonstrated. X-ray analysis of a representative macrocyclic tetralactone was also reported.     

Diastereoselective synthesis of strained spiro-cyclopropanooxindoles from cyclic diazoamides

Reaction of cyclic diazoamides and cyclic olefins or heteroaromatic systems using copper(I) triflate as a catalyst furnished a variety of strained spiro-cyclopropanooxindoles in a diastereoselective manner under mild reaction conditions. The effect of copper(I) triflate and rhodium(II) acetate catalysts on the cyclopropanation was also studied.     

Characterization of α and γ polymorphs of glycine crystallized from water‐ammonia solution

Crystallization of metastable α and stable γ polymorphs of glycine was carried out from aqueous solution in the presence of ammonia. Pure aqueous solution and solution with lower concentration of ammonia yield α nucleation and solution with a critical concentration of ammonia yield γ nucleation. Variation in the solubility of glycine in double distilled water and pH of the resulting solution due to the ammonia incorporation was studied in a range of temperatures. The induction period for the α and γ nucleation in the solution was determined and its variation due to the ammonia incorporation was also studied. Single crystals of both the polymorphs were grown by slow evaporation method. Effect of ammonia concentration and the resultant pH of the solution on the nucleation, growth and morphology of the grown polymorphs were investigated. The unidirectional growth of the γ polymorph along the polar axis was revealed. X‐ray powder diffraction method was employed to distinguish both the polymorphs structurally. Their thermal stability above room temperature was studied by differential scanning calorimetry which revealed that the as‐grown γ polymorph transforms to α at 179.6 °C while the as‐grown α retains its phase until melting. The optical transmittance of the grown γ polymorph was studied in the UV‐Vis‐Near IR region. The second harmonic generation (SHG) efficiency of the grown γ polymorph was studied with a Nd:YAG laser source and is about 6.8% higher than that of the inorganic standard KDP. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ring opening reaction of furan with high regio- and diastereo-selectivity via controlled addition of isatin-derived diazoamides

Reaction of cyclic diazoamides with furan systems using rhodium(II) acetate as a catalyst afforded a variety of (3Z)-3-[(2E)-4-oxopent-2-en-1-ylidene]indol-2-ones in a regio- and diastereo-selective manner. The diastereoselectivity was based on the flow rate of cyclic diazoamides. The representative products were characterized by single-crystal X-ray analyses.