@article{sanchez_leggett_sankar_2005, title={Analyzing water soluble soil organics as trifluoroacetyl derivatives by liquid state proton nuclear magnetic resonance}, volume={36}, ISSN={["1532-2416"]}, DOI={10.1080/00103620500304150}, abstractNote={Abstract In forested ecosystems, water soluble organics play an important role in soil processes including carbon and nutrient turnover, microbial activity and pedogenesis. The quantity and quality (i.e., chemistry) of these materials is sensitive to land management practices. Monitoring alterations in the chemistry of water soluble organics resulting from land management practices is difficult because of the complexity and low concentration of these compounds. A procedure is described in which the water soluble organics are quantitatively derivatized with trifluoroacetic anhydride and then analyzed by liquid state proton nuclear magnetic resonance (1H NMR). The procedure was applied to sample amounts as low as 0.03 mg from the forest floor and root exudates. The root exudate samples were dominated by aliphatic compounds with relatively few O‐alkyl, olefinic and aromatic compounds. The chemistry of the samples originating from the forest floor differed dramatically with soil texture and treatment combinations.}, number={19-20}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Sanchez, FG and Leggett, ZH and Sankar, S}, year={2005}, pages={2793–2805} }
 @article{karnati_gao_gao_yang_ni_sankar_wang_2002, title={A glucose-selective fluorescence sensor based on boronic acid-diol recognition}, volume={12}, ISSN={["0960-894X"]}, DOI={10.1016/S0960-894X(02)00767-9}, abstractNote={A glucose selective diphenylboronic acid fluorescent sensor (10a) with a K(a) of 1472M(-1) has been synthesized and evaluated. This sensor shows a 43- and 49-fold selectivity for glucose over fructose and galactose, respectively. The binding affinity improvement is about 300-fold and the selectivity improvement for glucose over fructose is about 1400-fold compared with the monoboronic acid compound, phenylboronic acid. 1H NMR studies indicate that sensor 10a binds with alpha-D-glucofuranose in a bidentate manner (1:1 ratio).}, number={23}, journal={BIOORGANIC & MEDICINAL CHEMISTRY LETTERS}, author={Karnati, VV and Gao, XM and Gao, SH and Yang, WQ and Ni, WJ and Sankar, S and Wang, BH}, year={2002}, month={Dec}, pages={3373–3377} }
 @article{shull_spielvogel_gopalaswamy_sankar_boyle_head_devito_2000, title={Evidence for spontaneous, reversible paracyclophane formation. Aprotic solution structure of the boron neutron capture therapy drug, L-p-boronophenylalanine}, ISSN={["0300-9580"]}, DOI={10.1039/a906038c}, abstractNote={The simple, straightforward 1H NMR spectrum of the neutron capture therapy drug, L-p-boronophenylalanine (L-p-BPA), in D2O changes to a more complex one in DMSO-d6 in which the ratio of new species observed is highly concentration dependent. The new species detected can only be explained by an additional stereocenter being formed at the boron center by intermolecular chelation of the amino acid of another molecule of L-p-BPA. This gives rise to the presence of an oligomeric species as well as another whose aromatic protons appear as a pair of sharp AB quartets centered further upfield at 6.66 and 6.84. Due to these shifts and couplings observed between the benzylic protons and the proton at the stereocenter of the amino acid, it is proposed that this species is a paracyclophane dimer of L-p-BPA in which one molecule of L-p-BPA chelates head-to-tail with another. This cyclophane dimer predominates in low concentrations ( 90 mM) concentrations. The formation of these two species is completely reversible, the addition of D2O completely regenerating L-p-BPA. Variable temperature 1H NMR found that the two pairs of aromatic protons of the cyclophane dimer coalesce at Tc = 141 °C, corresponding to a ΔG‡ = 20.6 kcal mol−1.}, number={3}, journal={JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2}, author={Shull, BK and Spielvogel, DE and Gopalaswamy, R and Sankar, S and Boyle, PD and Head, G and Devito, K}, year={2000}, pages={557–561} }
 @article{shull_spielvogel_head_gopalaswamy_sankar_devito_2000, title={Studies on the structure of the complex of the boron neutron capture therapy drug, L-p-boronophenylalanine, with fructose and related carbohydrates: Chemical and C-13 NMR evidence for the beta-D-fructofuranose 2,3,6-(p-phenylalanylorthoboronate) structure}, volume={89}, DOI={10.1002/(sici)1520-6017(200002)89:2<215::aid-jps8>3.0.co;2-p}, abstractNote={The complex of L-L-boronophenylalanine (L-p-BPA) with fructose has been used for the past 5 years in clinical trials of boron neutron capture therapy to treat both melanoma and glioblastoma multiforme. However, the structure of this complex in water buffered at physiologic pH has not been established. In the (1)H NMR spectra (D(2)O buffered at pD 7.4) of the complex of L-p-BPA with various carbohydrates, the upfield chemical shifts of the aromatic protons of L-p-BPA confirm that the boron atom is negatively charged and tetrahedral. In the (13)C NMR spectrum of the complex of L-p-BPA with U-(13)C labeled fructose, the chemical shifts and (1)J(CC) coupling constants are consistent with fructose adopting the beta-D-fructofuranose form. In addition, the (1)J(CC) coupling constants along with the binding constants measured for L-p-BPA with a series of monosaccharides and disaccharides seem to suggest that the beta-D-fructofuranose 2,3,6-(p-phenylalanylorthoboronate) structure strongly predominates, with free L-p-BPA and fructose the only other species detected.}, number={2}, journal={Journal of Pharmaceutical Sciences}, author={Shull, B. K. and Spielvogel, D. E. and Head, C. and Gopalaswamy, R. and Sankar, S. and Devito, K.}, year={2000}, pages={215–222} }