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Saponins are widely distributed in plant kingdom. In view of their wide range of biological activities and occurrence as complex mixtures, saponins have been purified and separated by high-performance liquid chromatography using reverse-phase columns at lower wavelength. Mostly, saponins are not detected by ultraviolet detector due to lack of chromophores. Electrospray ionization mass spectrometry, diode array detector , evaporative light scattering detection, and charged aerosols have been used for overcoming the detection problem of saponins.

Department of Chemistry, H. N. B. Garhwal University, Srinagar (Garhwal)-246 174, Uttarakhand, India E-mail : msmrawat@gmail.com; geeta_joshi4f54@rediffmail.com Department of Physics, H. N. B. Garhwal University, Srinagar (Garhwal)-246 174, Uttarakhand, India Manuscript received 20 December 2013, accepted 20 January 2014 The pyrazolines are well known fluorescent brightening agents and are used as chemosensors. The reaction of dibenzalacetone with hydrazine hydrate and acetic acid yielded a mixture of two products (1 and 2), purified by centrifugal chromatographic separation using chromatotron. Compound 1 was characterized as 5-phenyl-3-[(E)-2- phenylvinyl]-4,5-dihydro-1H-pyrazole-1-methylcarbaldehyde by ESI-MS, FT-IR, UV, fluorescence spectroscopy, 1H NMR data and microanalysis. The fluorescence quantum yield has been determined in various solvents and ratio of excited state dipole moment to ground state dipole moment has been determined using solvatochromic method. The compound can be used as efficient fluorescent material in ultraviolet range.

Reaction of dibenzalacetone with hydrazine hydrate and formic acid yielded a novel 2-pyrazoline 1 , characterized by ESI-MS, FT-IR, UV, 1 HNMR and 13 CNMR data and microanalysis. Keywords: dibenzalacetone; hydrazine hydrate; pyrazoline; 5-phenyl-3-[( E )-2-phenyl-vinyl]-4,5-dihydro-1 H -pyrazole-1-carbaldehyde; fluorescence Introduction Substituted pyrazolines are useful in pharmaceutical and agrochemical research. Pyrazoline derivatives with a phenyl group at the 5-position possess good film-forming properties, exhibit excellent characteristics of blue photoluminescence and electroluminescence [1]. Pyrazolines are also used as optical brighteners and whiteners. Pyrazolines display various biological activities such as antimicrobial [2], antifungal [3], antidepressant [4], immunosuppressive [5], anticonvulsant [6], anti-tumor [7], antiamoebic [8], antibacterial [9] and antiinflammatory [10] activities. Syntheses of pyrazolines by reaction of α,β-unsaturated carbonyl compounds with diazoalkanes [11] or with hydrazine hydrate [12,13] were reported in literature. N-Substituted thiocarbamoyl-3,5-diphenyl-2-pyrazoline derivatives having NS donor, their palladium II complexes [14] and hydroxyl phenyl pyrazolines have also been synthesized [15]. The reaction of