01818nas a2200157   4500008004100000022001400041245013700055210006900192260000900261300001400270490000700284520120200291100002401493700001701517856012601534       2020                        eng d  a0003-270000aEnantioselective separation using chiral amino acid functionalized polyfluorene coated on mesoporous anodic aluminum oxide membranes0 aEnantioselective separation using chiral amino acid functionaliz  cMAY   a6850-68570 v923 a<p>Homochiral mesoporous anodic aluminum oxide membranes (AAO) were prepared by coating protected chiral D/L aspartic acid appended polyfluorene in the pores. These chiral AAO membranes successfully demonstrated enantioselective recognition and separation of a range of amino acids from their aqueous racemic mixture by simple filtration. Enantioselective separation was achieved by selective adsorption of one enantiomer from the aqueous racemic mixture into the chiral pores of the AAO membrane leaving the filtrate enriched with the other enantiomer. Extraction and quantification of the adsorbed amino acid (glutamic acid) demonstrated that 1 mg of homochiral polyfluorene could effectively extract about 3.5 mg of glutamic acid with 95% enantiomeric excess in 24 h. This is one of the highest enantiomeric excesses (ee %) and yields reported so far in the literature for a racemic mixture of glutamic acid. The pore size of the AAO membrane influenced the efficiency of separation with a reduction in pore size from 200 to 20 nm leading to reduced ee % (similar to 95% to similar to 28%). These results raise the possibility for a facile method to carry out enantioselective separation.</p>
1 aNikam, Shrikant, B.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/enantioselective-separation-using-chiral-amino-acid-functionalized-polyfluorene-coated02533nas a2200277   4500008004100000245016800041210006900209260000800278300001200286490000700298520154600305653003001851653001901881653002101900653002201921653001601943653001501959100002401974700002501998700002402023700002402047700001702071700002402088700002402112856011902136       2020                        eng d00aFive concomitant polymorphs of a green fluorescent protein chromophore (GFPc) analogue: understanding variations in photoluminescence with pi-stacking interactions0 aFive concomitant polymorphs of a green fluorescent protein chrom  cOCT  a850-8640 v763 a<p>The synthetically modified green fluorescent protein chromophore analogue 3,4,5-trimethoxybenzylidene imidazolinone (1) yielded five polymorphs (I, II, III, IV, V) concomitantly irrespective of the solvent used for crystallization. The pentamorphic modification of 1 is solely due to the interplay of iso-energetic weak intermolecular interactions in molecular associations as well as the conformational flexibility offered by a C-C single bond, which connects the electron-deficient moiety imidazolinone with the electron-rich trimethoxybenzylidene group. A common structural feature observed in all the polymorphs is the formation of a `zero-dimensional' centrosymmetric dimeric unit through a short and linear C-H center dot center dot center dot O hydrogen bond engaging phenyl C-H and imidazolinone carbonyl oxygen. However, the networking of these dimeric units showed a subtle difference in all the polymorphs. The 2D isostructurality was observed between polymorphs I, II and III, while the other two polymorphs IV and V revealed only `zero-dimensional' isostructurality. The different fluorescence emissions of Form I (blue) and Forms II to V (yellow) were attributed to the differences in pi-stacking interactions. It shows that one can modulate the photophysical properties of these smart materials by slightly altering their crystal structure. Such an approach will aid in developing new multi-colour organic fluorescent materials of varying crystal structures for live-cell imaging and fluorescent sensing applications.</p>
10agreen fluorescent protein10ahydrogen bonds10aisostructurality10aphotoluminescence10api-stacking10aPolymorphs1 aMali, Bhupendra, P.1 aDash, Soumya, Ranjan1 aNikam, Shrikant, B.1 aPuthuvakkal, Anisha1 aVanka, Kumar1 aManoj, Kochunnoonny1 aGonnade, Rajesh, G.  uhttps://library.ncl.res.in/content/five-concomitant-polymorphs-green-fluorescent-protein-chromophore-gfpc-analogue00626nas a2200145   4500008004100000022001400041245016100055210006900216260000900285300001000294490000700304100002400311700001700335856012800352       2021                        eng d  a0003-270000aEnantioselective separation using chiral amino acid functionalized polyfluorene coated on mesoporous anodic aluminum oxide membranes (vol 92, pg 6850, 2020)0 aEnantioselective separation using chiral amino acid functionaliz  cJUL   a103880 v931 aNikam, Shrikant, B.1 aAsha, S., K.  uhttps://library.ncl.res.in/content/enantioselective-separation-using-chiral-amino-acid-functionalized-polyfluorene-coated-006205nas a2200145   4500008004100000245013700041210006900178260000800247300001400255490000600269520561500275100002405890700001605914856012905930       2022                        eng d00aEnantioselective separation of amino acids using chiral polystyrene microspheres synthesized by a post-polymer modification approach0 aEnantioselective separation of amino acids using chiral polystyr  cMAR  a257–2650 v23 a<p>
	<span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">The enantioselective separation of a racemic mixture of amino acids was achieved by chiral amino acid-modified polystyrene (PS) that was developed by a post-polymer modification approach. Styrene was polymerized using the reversible addition–fragmentation chain-transfer (RAFT) polymerization technique and further post-polymer modification was applied by Friedel–Crafts acylation reaction with chiral&nbsp;</span><i style="box-sizing: border-box; outline: none; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">N</i><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-phthaloyl-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-leucine acid chloride to obtain the protected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu. The chiral PS (protected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu) was assembled into microspheres using a surfactant and was used for carrying out the enantioselective separation of amino acid racemic mixtures by enantioselective adsorption followed by a simple filtration process. Compared to as-precipitated chiral PS (protected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu) powder, the protected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu microspheres exhibited a better enantioselective separation efficiency (ee %). Furthermore, the protected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu was deprotected to obtain the amine-functionalized deprotected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu chiral PS, which was also assembled into microspheres and used for carrying out enantioselective separation. Deprotected PS-</span><span class="smallcaps smallerCapital" style="box-sizing: border-box; outline: none; font-variant-numeric: normal; font-variant-east-asian: normal; font-variant-caps: small-caps; font-variant-alternates: normal; color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">l</span><span style="color: rgb(0, 0, 0); font-family: georgia, serif; font-size: 17.008px; background-color: rgb(244, 244, 244);">-Leu-functionalized chiral PS microspheres could achieve up to 81.6 ee % for the enantioselective separation of a racemic mixture of leucine. This is one of the first reports of the synthesis of amino acid-modified chiral PS microspheres and their application to the simple filtration-based enantioselective separation of native amino acids from their racemic mixtures.</span></p>
1 aNikam, Shrikant, B.1 aK, Asha, S.  uhttps://library.ncl.res.in/content/enantioselective-separation-amino-acids-using-chiral-polystyrene-microspheres-synthesized02499nas a2200241   4500008004100000022001400041245010600055210006900161260000900230300001100239490000800250520167900258653001101937653000801948653004201956653002301998653002102021100002402042700003002066700002602096700001702122856011802139       2022                        eng d  a0014-305700aStructure-property insights into chiral thiophene copolymers by direct heteroarylation polymerization0 aStructureproperty insights into chiral thiophene copolymers by d  cDEC   a1116760 v1813 a<p>
	Chiral thiophene copolymers with fluorene as co monomer are designed having N-Boc-L-glutamic acid-1-tert-butyl ester as a chiral substituent located either on the thiophene unit or the fluorene unit with varying spacer length. The atom-economic direct heteroarylation polymerization (DHAP) method is utilized for the polymerization. Gibb's free energy (delta G) for polymerization determined using DFT calculations indicate difficulty in achieving high molar mass when the bulky chiral substituents are attached through short spacer to the backbone. The experimental observations are in agreement with the theoretical calculations with no polymer-ization or very low molar mass sticky compounds obtained for reactions with predicted + &amp; UDelta;G values. Structure -property relationship are compared for two chiral polymers -P4 and P5 having the chiral substitution on thiophene and fluorene units respectively. No CD signal is observed in THF-a good solvent where the polymers are molecularly dissolved. Intense bisignated CD signal is observed for both polymers upon addition of methanol - a poor solvent, to their THF solution. The bisignate CD signal with maxima at lower wavelength and inflection point associated with the pi-pi* absorption band is characteristic of exciton coupling between polymer chains in a left handed helical orientation. Small differences are observed in the intensity of the CD signal for the polymers P4 and P5 highlighting the impact of steric hindrance of bulky pendant groups on polymer conformation. DHAP is an atom economic polymerization procedure that can be gainfully utilized for developing chiral conjugated polymers.</p>
10achiral10aDFT10aDirect heteroarylation polymerization10aGibb?s free energy10aSteric Hindrance1 aNikam, Shrikant, B.1 aSingh, Chandrodai, Pratap1 aKrishnamurty, Sailaja1 aAsha, S., K.  uhttps://library.ncl.res.in/content/structure-property-insights-chiral-thiophene-copolymers-direct-heteroarylation