@article{taniguchi_ptaszek_chandrashaker_lindsey_2017, title={The Porphobilinogen Conundrum in Prebiotic Routes to Tetrapyrrole Macrocycles}, volume={47}, ISSN={["1573-0875"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84969780645&partnerID=MN8TOARS}, DOI={10.1007/s11084-016-9506-1}, abstractNote={Attempts to develop a credible prebiotic route to tetrapyrroles have relied on enzyme-free recapitulation of the extant biosynthesis, but this process has foundered from the inability to form the pyrrole porphobilinogen (PBG) in good yield by self-condensation of the precursor δ-aminolevulinic acid (ALA). PBG undergoes robust oligomerization in aqueous solution to give uroporphyrinogen (4 isomers) in good yield. ALA, PBG, and uroporphyrinogen III are universal precursors to all known tetrapyrrole macrocycles. The enzymic formation of PBG entails carbon-carbon bond formation between the less stable enolate/enamine of one ALA molecule (3-position) and the carbonyl/imine (4-position) of the second ALA molecule; without enzymes, the first ALA reacts at the more stable enolate/enamine (5-position) and gives the pyrrole pseudo-PBG. pseudo-PBG cannot self-condense, yet has one open α-pyrrole position and is proposed to be a terminator of oligopyrromethane chain-growth from PBG. Here, 23 analogues of ALA have been subjected to density functional theoretical (DFT) calculations, but no motif has been identified that directs reaction at the 3-position. Deuteriation experiments suggested 5-(phosphonooxy)levulinic acid would react preferentially at the 3- versus 5-position, but a hybrid condensation with ALA gave no observable uroporphyrin. The results suggest efforts toward a biomimetic, enzyme-free route to tetrapyrroles from ALA should turn away from structure-directed reactions and focus on catalysts that orient the two aminoketones to form PBG in a kinetically controlled process, thereby avoiding formation of pseudo-PBG.}, number={1}, journal={ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES}, publisher={Springer Nature}, author={Taniguchi, Masahiko and Ptaszek, Marcin and Chandrashaker, Vanampally and Lindsey, Jonathan S.}, year={2017}, month={Mar}, pages={93–119} }
 @article{liu_chen_mandal_chandrashaker_evans-storms_pitner_bocian_holten_lindsey_2016, title={Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, red-emitting chlorins}, volume={40}, ISSN={["1369-9261"]}, DOI={10.1039/c6nj01154c}, abstractNote={PEGylated chlorins are soluble in water, can be excited in the near-ultraviolet, and exhibit a relatively narrow fluorescence band in the red spectral region.}, number={9}, journal={NEW JOURNAL OF CHEMISTRY}, author={Liu, Mengran and Chen, Chih-Yuan and Mandal, Amit Kumar and Chandrashaker, Vanampally and Evans-Storms, Rosemary B. and Pitner, J. Bruce and Bocian, David F. and Holten, Dewey and Lindsey, Jonathan S.}, year={2016}, pages={7721–7740} }
 @article{deans_taniguchi_chandrashaker_ptaszek_lindsey_2016, title={Complexity in structure-directed prebiotic chemistry. Reaction bifurcation from a beta-diketone in tetrapyrrole formation}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979074707&partnerID=MN8TOARS}, DOI={10.1039/c6nj00545d}, abstractNote={An unsymmetrical β-diketone with δ-aminolevulinic acid affords both a “defective” and a “normal” pyrrole; upon combinatorial reaction the former terminates chain-growth of the latter on the path to tetrapyrrole macrocycles.}, number={7}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Deans, Richard M. and Taniguchi, Masahiko and Chandrashaker, Vanampally and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2016}, month={Jul}, pages={6434–6440} }
 @article{deans_taniguchi_chandrashaker_ptaszek_chambers_soares_lindsey_2016, title={Complexity in structure-directed prebiotic chemistry. Unexpected compositional richness from competing reactants in tetrapyrrole formation}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979079544&partnerID=MN8TOARS}, DOI={10.1039/c6nj00543h}, abstractNote={Acyclic reactants afford “partially defective” pyrroles that interfere with chain growth of “normal” pyrroles on the path to tetrapyrrole macrocycles.}, number={7}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Deans, Richard M. and Taniguchi, Masahiko and Chandrashaker, Vanampally and Ptaszek, Marcin and Chambers, Dana R. and Soares, Ana R. M. and Lindsey, Jonathan S.}, year={2016}, month={Jul}, pages={6421–6433} }
 @article{taniguchi_deans_chandrashaker_ptaszek_lindsey_2016, title={Scope and limitations of two model prebiotic routes to tetrapyrrole macrocycles}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84984911595&partnerID=MN8TOARS}, DOI={10.1039/c6nj01423b}, abstractNote={Aqueous reaction (35 °C, 72 h) of two acyclic compounds, an α-aminoketone + β-ketoester or β-diketone (not shown), affords a pyrrole that self-condenses to give the porphyrinogen.}, number={9}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Taniguchi, Masahiko and Deans, Richard M. and Chandrashaker, Vanampally and Ptaszek, Marcin and Lindsey, Jonathan S.}, year={2016}, pages={7445–7455} }
 @article{chandrashaker_ptaszek_taniguchi_lindsey_2016, title={Synthesis of diverse acyclic precursors to pyrroles for studies of prebiotic routes to tetrapyrrole macrocycles}, volume={40}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84990050463&partnerID=MN8TOARS}, DOI={10.1039/c6nj02048h}, abstractNote={Some 50 ketones, β-diketones, β-ketoesters and α-aminoketones have been prepared for studies of the formation of trisubstituted pyrroles equipped for self-condensation leading to tetrapyrrole macrocycles.}, number={10}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Chandrashaker, Vanampally and Ptaszek, Marcin and Taniguchi, Masahiko and Lindsey, Jonathan S.}, year={2016}, pages={8786–8808} }
 @article{deans_chandrashaker_taniguchi_lindsey_2015, title={Complexity in structure-directed prebiotic chemistry. Effect of a defective competing reactant in tetrapyrrole formation}, volume={39}, ISSN={["1369-9261"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84945937304&partnerID=MN8TOARS}, DOI={10.1039/c5nj01474c}, abstractNote={A reactive but defective pyrrole, derived from the simple β-diketone acetylacetone, terminates chain-growth in a quantitative combinatorial manner in tetrapyrrole formation.}, number={11}, journal={NEW JOURNAL OF CHEMISTRY}, publisher={Royal Society of Chemistry (RSC)}, author={Deans, Richard M. and Chandrashaker, Vanampally and Taniguchi, Masahiko and Lindsey, Jonathan S.}, year={2015}, pages={8273–8281} }
 @article{ra_gauger_muthukumaran_balasubramanian_chandrashaker_taniguchi_yu_talley_ehudin_ptaszek_et al._2015, title={Progress towards synthetic chlorins with graded polarity, conjugatable substituents, and wavelength tunability}, volume={19}, ISSN={["1099-1409"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85027922166&partnerID=MN8TOARS}, DOI={10.1142/s1088424615500042}, abstractNote={ Advances in chlorin synthetic chemistry now enable the de novo preparation of diverse chlorin-containing molecular architectures. Five distinct molecular designs have been explored here, including hydrophobic bioconjugatable (oxo)chlorins; a hydrophilic bioconjugatable chlorin; a trans-ethynyl/iodochlorin building block; a set of chlorins bearing electron-rich (methoxy, dimethylamino, methylthio) groups at the 3-position; and a set of ten 3,13-disubstituted chlorins chiefly bearing groups with extended π-moieties. Altogether 23 new chlorins (17 targets, 6 intermediates) have been prepared. The challenge associated with molecular designs that encompass the combination of "hydrophilic, bioconjugatable and wavelength-tunable" chiefly resides in the nature of the hydrophilic unit. }, number={4}, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, publisher={World Scientific Pub Co Pte Lt}, author={Ra, Doyoung and Gauger, Kelly A. and Muthukumaran, Kannan and Balasubramanian, Thiagarajan and Chandrashaker, Vanampally and Taniguchi, Masahiko and Yu, Zhanqian and Talley, Daniel C. and Ehudin, Melanie and Ptaszek, Marcin and et al.}, year={2015}, month={Apr}, pages={547–572} }
 @article{alexy_yuen_chandrashaker_diers_kirmaier_bocian_holten_lindsey_2014, title={Panchromatic absorbers for solar light-harvesting}, volume={50}, ISSN={["1364-548X"]}, DOI={10.1039/c4cc06853j}, abstractNote={A set of panchromatic absorbers exhibiting long excited-state lifetimes in both polar and nonpolar media has been prepared. The architectures are based on a porphyrin strongly coupled electronically to 1-4 perylene-monoimides via ethyne linkers. The constructs should find utility in molecular solar-conversion systems.}, number={93}, journal={CHEMICAL COMMUNICATIONS}, author={Alexy, Eric J. and Yuen, Jonathan M. and Chandrashaker, Vanampally and Diers, James R. and Kirmaier, Christine and Bocian, David F. and Holten, Dewey and Lindsey, Jonathan S.}, year={2014}, pages={14512–14515} }