@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} }
 @misc{lindsey_muthukumaran_m._huma_2009, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,595,407}, number={2009 Sep. 29}, author={Lindsey, J. S. and Muthukumaran, K. Ptaszek and M. and Huma, H. Z. S.}, year={2009} }
 @misc{balakumar_muthukumaran_lindsey_2009, title={Route to formyl-porphyrins}, volume={7,501,507}, number={2009 Mar 10}, author={Balakumar, A. and Muthukumaran, K. and Lindsey, J. S.}, year={2009} }
 @misc{lindsey_loewe_muthukumaran_ambroise_2009, title={Synthesis of phosphono-substituted porphyrin compounds for attachment to metal oxide surfaces}, volume={7,553,977}, number={2009 Jun 30}, author={Lindsey, J. S. and Loewe, R. S. and Muthukumaran, K. and Ambroise, A.}, year={2009} }
 @misc{lindsey_muthukumaran_ptaszek_huma_2008, title={Boron complexation strategy for use in manipulating 1-acyldipyrromethanes}, volume={7,423,160}, number={2008 Sep. 9}, author={Lindsey, J. S. and Muthukumaran, K. and Ptaszek, M. and Huma, H. Z. S.}, year={2008} }
 @misc{lahaye_muthukumaran_hung_gryko_reboucas_spasojevic_batinic-haberle_lindsey_2007, title={Design and synthesis of manganese porphyrins with tailored lipophilicity: Investigation of redox properties and superoxide dismutase activity}, volume={15}, ISSN={["1464-3391"]}, DOI={10.1016/j.bmc.2007.07.015}, abstractNote={Thirteen new manganese porphyrins and two porphodimethenes bearing one to three different substituents at the meso positions in a variety of architectures have been synthesized. The substituents employed generally are (i) electron-withdrawing to tune the reduction potential to the desirable range (near +0.3 V vs NHE), and/or (ii) lipophilic to target the interior of lipid bilayer membranes and/or the blood–brain barrier. The influence of the substituents on the MnIII/MnII reduction potentials has been characterized, and the superoxide dismutase activity of the compounds has been examined.}, number={22}, journal={BIOORGANIC & MEDICINAL CHEMISTRY}, author={Lahaye, Dorothee and Muthukumaran, Kannan and Hung, Chen-Hsiung and Gryko, Dorota and Reboucas, Julio S. and Spasojevic, Ivan and Batinic-Haberle, Ines and Lindsey, Jonathan S.}, year={2007}, month={Nov}, pages={7066–7086} }
 @article{sharada_muresan_muthukumaran_lindsey_2005, title={Direct synthesis of palladium porphyrins from acyldipyrromethanes}, volume={70}, ISSN={["1520-6904"]}, DOI={10.1021/jo050120v}, abstractNote={[reaction: see text] Palladium porphyrins are valuable photosensitizers and luminescent agents in biology and materials chemistry. New methodology is described wherein a 1-acyldipyrromethane is converted into the palladium chelate of a trans-A(2)B(2) porphyrin via a one-flask reaction. The reaction entails self-condensation of the 1-acyldipyrromethane in refluxing ethanol containing KOH (5-10 mol equiv) and Pd(CH(3)CN)(2)Cl(2) (0.6 mol equiv) exposed to air. This direct route to palladium porphyrins is more expedient than the four steps of the traditional synthesis: (1) reduction of the 1-acyldipyrromethane; (2) acid-catalyzed condensation; (3) oxidation of the porphyrinogen intermediate; and (4) metal insertion. The new synthesis requires neither acid nor DDQ and formally entails only a 2e(-) + 2H(+) oxidation overall versus the traditional multistep synthesis which requires a 2e(-) + 2H(+) reduction per each 1-acyldipyrromethane (4e(-) + 4H(+) overall) followed by a 6e(-) + 6H(+) oxidation. The analogous reaction of a 1,9-diacyldipyrromethane and a dipyrromethane also gives the palladium porphyrin. Seven palladium porphyrins have been prepared in yields of 25-57%. The direct route also can be used with Cu(OAc)(2).H(2)O to give the copper porphyrin albeit in low yield. In summary, this methodology readily affords palladium porphyrins directly from acyldipyrromethanes.}, number={9}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Sharada, DS and Muresan, AZ and Muthukumaran, K and Lindsey, JS}, year={2005}, month={Apr}, pages={3500–3510} }
 @article{zaidi_muthukumaran_tamaru_lindsey_2004, title={9-Acylation of 1-acyldipyrromethanes containing a dialkylboron mask for the alpha-acylpyrrole motif}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo048587d}, abstractNote={1,9-Diacyldipyrromethanes are important precursors to porphyrins, yet synthetic access remains limited owing to (1) poor conversion in the 9-acylation of 1-acyldipyrromethanes and (2) handling difficulties because acyldipyrromethanes typically streak upon chromatography and give amorphous powders upon attempted crystallization. A reliable means for converting a dipyrromethane to a 1-acyldipyrromethane−dialkylboron complex was recently developed, where the dialkylboron (BR2) unit renders the complex hydrophobic and thereby facilitates isolation. Herein a refined preparation of 1,9-diacyldipyrromethanes is presented that employs the 1-acyldipyrromethane−BR2 complex as a substrate for 9-acylation. The dialkylboron unit provides protection for the α-acylpyrrole unit. 9-Acylation requires formation of the pyrrolyl−MgBr reagent and the presence of 1 equiv of a nonnucleophilic base to quench the proton liberated upon α-acylation. Reaction of the 1-acyldipyrromethane−BR2 complex (1 equiv) with mesitylmagnesium br...}, number={24}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Zaidi, SHH and Muthukumaran, K and Tamaru, S and Lindsey, JS}, year={2004}, month={Nov}, pages={8356–8365} }
 @article{balakumar_muthukumaran_lindsey_2004, title={A new route to meso-formyl porphyrins}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo049819b}, abstractNote={Prior syntheses of porphyrins bearing meso-formyl groups have generally employed the Vilsmeier formylation of an acid-resistant copper or nickel porphyrin. A new approach for the synthesis of free base porphyrins bearing one or two (cis or trans) meso-formyl substituents entails the use of a dipyrromethane bearing an acetal group at the 5-position, a dipyrromethane-1-carbinol bearing an acetal group at the 5-position or carbinol position, or a dipyrromethane-1,9-dicarbinol bearing an acetal group at a carbinol position. Treatment of the resulting meso-acetal-substituted free base porphyrin to gentle acidic hydrolysis yields the corresponding meso-formyl porphyrin.}, number={15}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Balakumar, A and Muthukumaran, K and Lindsey, JS}, year={2004}, month={Jul}, pages={5112–5115} }
 @article{tamaru_yu_youngblood_muthukumaran_taniguchi_lindsey_2004, title={A tin-complexation strategy for use with diverse acylation methods in the preparation of 1,9-diacyldipyrromethanes}, volume={69}, ISSN={["0022-3263"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0842285782&partnerID=MN8TOARS}, DOI={10.1021/jo035622s}, abstractNote={The acylation of dipyrromethanes to form 1,9-diacyldipyrromethanes is an essential step in the rational synthesis of porphyrins. Although several methods for acylation are available, purification is difficult because 1,9-diacyldipyrromethanes typically streak extensively upon chromatography and give amorphous powders upon attempted crystallization. A solution to this problem has been achieved by reacting the 1,9-diacyldipyrromethane with Bu(2)SnCl(2) to give the corresponding dibutyl(5,10-dihydrodipyrrinato)tin(IV) complex. The reaction is selective for dipyrromethanes that bear acyl groups at both the 1- and 9-positions but otherwise is quite tolerant of diverse substituents. The diacyldipyrromethane-tin complexes are stable to air and water, are highly soluble in common organic solvents, crystallize readily, and chromatograph without streaking. Four methods (Friedel-Crafts, Grignard, Vilsmeier, benzoxathiolium salt) were examined for the direct 1,9-diacylation of a dipyrromethane or the 9-acylation of a 1-acyldipyrromethane. In each case, treatment of the crude reaction mixture with Bu(2)SnCl(2) and TEA at room temperature enabled facile isolation of multigram quantities of the 1,9-diacyldipyrromethane-tin complex. The diacyldipyrromethane-tin complexes could be decomplexed with TFA in nearly quantitative yield. Alternatively, use of a diacyldipyrromethane-tin complex in a porphyrin-forming reaction (reduction with NaBH(4), acid-catalyzed condensation with a dipyrromethane, DDQ oxidation) afforded the desired free base porphyrin in yield comparable to that obtained from the uncomplexed diacyldipyrromethane. The acylation/tin-complexation strategy has been applied to a bis(dipyrromethane) and a porphyrin-dipyrromethane. In summary, the tin-complexation strategy has broad scope, is compatible with diverse acylation methods, and greatly facilitates access to 1,9-diacyldipyrromethanes.}, number={3}, journal={JOURNAL OF ORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Tamaru, S and Yu, LH and Youngblood, WJ and Muthukumaran, K and Taniguchi, M and Lindsey, JS}, year={2004}, month={Feb}, pages={765–777} }
 @article{muthukumaran_ptaszek_noll_scheidt_lindsey_2004, title={Boron-complexation strategy for use with 1-acyldipyrromethanes}, volume={69}, ISSN={["1520-6904"]}, DOI={10.1021/jo0492620}, abstractNote={1-Acyldipyrromethanes are important precursors in rational syntheses of diverse porphyrinic compounds. 1-Acyldipyrromethanes are difficult to purify, typically streaking upon chromatography and giving amorphous powders upon attempted crystallization. A solution to this problem has been achieved by reacting the 1-acyldipyrromethane with a dialkylboron triflate (e.g., Bu2B-OTf or 9-BBN-OTf) to give the corresponding B,B-dialkyl-B-(1-acyldipyrromethane)boron(III) complex. The reaction is selective for a 1-acyldipyrromethane in the presence of a dipyrromethane. The 1-acyldipyrromethane-boron complexes are stable to routine handling, are soluble in common organic solvents, are hydrophobic, crystallize readily, and chromatograph without streaking. The 1-acyldipyrromethane can be liberated in high yield from the boron complex upon treatment with 1-pentanol. Alternatively, the 1-acyldipyrromethane-boron complex can be used in the formation of a trans-A2B2-porphyrin. In summary, the boron-complexation strategy has broad scope and greatly facilitates the isolation of 1-acyldipyrromethanes.}, number={16}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Muthukumaran, K and Ptaszek, M and Noll, B and Scheidt, WR and Lindsey, JS}, year={2004}, month={Aug}, pages={5354–5364} }
 @article{li_surthi_mathur_gowda_zhao_sorenson_tenent_muthukumaran_lindsey_misra_2004, title={Multiple-bit storage properties of porphyrin monolayers on SiO2}, volume={85}, ISSN={["1077-3118"]}, DOI={10.1063/1.1782254}, abstractNote={Hybrid molecule-silicon capacitors have been fabricated by the self-assembly of a monolayer of porphyrin molecules on a silicon oxide surface. The porphyrin employed [5-(4-dihydroxyphosphorylphenyl)-10,15,20-trimesitylporphinatozinc(II)] attaches to silicon oxide via a phosphonate linkage. Cyclic voltammetry current and capacitance/conductance measurements have been used to characterize the capacitors. The presence of multiple distinct peaks in current density and capacitance/conductance measurements are associated with oxidation and reduction of the molecular monolayer. The charge-storage states of the capacitor indicate applicability for use in multiple-bit memory devices.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Li, QL and Surthi, S and Mathur, G and Gowda, S and Zhao, Q and Sorenson, TA and Tenent, RC and Muthukumaran, K and Lindsey, JS and Misra, V}, year={2004}, month={Sep}, pages={1829–1831} }
 @article{muthukumaran_loewe_ambroise_tamaru_li_mathur_bocian_misra_lindsey_2004, title={Porphyrins bearing arylphosphonic acid tethers for attachment to oxide surfaces}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo034945l}, abstractNote={Synthetic molecules bearing phosphonic acid groups can be readily attached to oxide surfaces. As part of a program in molecular-based information storage, we have developed routes for the synthesis of diverse porphyrinic compounds bearing phenylphosphonic acid tethers. The routes enable (1) incorporation of masked phosphonic acid groups in precursors for use in the rational synthesis of porphyrinic compounds and (2) derivatization of porphyrins with masked phosphonic acid groups. The precursors include dipyrromethanes, monoacyldipyrromethanes, and diacyldipyrromethanes. The tert-butyl group has been used to mask the dihydroxyphosphoryl substituent. The di-tert-butyloxyphosphoryl unit is stable to the range of conditions employed in syntheses of porphyrins and multiporphyrin arrays yet can be deprotected under mild conditions (TMS-Cl/TEA or TMS-Br/TEA in refluxing CHCl(3)) that do not cause demetalation of zinc or magnesium porphyrins. The porphyrinic compounds that have been prepared include (1) A(3)B-, trans-AB(2)C-, and ABCD-porphyrins that bear a single phenylphosphonic acid group, (2) a trans-A(2)B(2)-porphyrin bearing two phenylphosphonic acid groups, (3) a chlorin that bears a single phenylphosphonic acid group, and (4) a porphyrin dyad bearing a single phenylphosphonic acid group. For selected porphyrin-phosphonic acids, the electrochemical characteristics have been investigated for molecules tethered to SiO(2) surfaces grown on doped Si. The voltammetric behavior indicates that the porphyrin-phosphonic acids form robust, electrically well-behaved monolayers on the oxide surface.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Muthukumaran, K and Loewe, RS and Ambroise, A and Tamaru, SI and Li, QL and Mathur, G and Bocian, DF and Misra, V and Lindsey, JS}, year={2004}, month={Mar}, pages={1444–1452} }
 @article{loewe_ambroise_muthukumaran_padmaja_lysenko_mathur_li_bocian_misra_lindsey_2004, title={Porphyrins bearing mono or tripodal benzylphosphonic acid tethers for attachment to oxide surfaces}, volume={69}, ISSN={["1520-6904"]}, DOI={10.1021/jo034946d}, abstractNote={The ability to attach redox-active molecules to oxide surfaces in controlled architectures (distance, orientation, packing density) is essential for the design of a variety of molecular-based information storage devices. We describe the synthesis of a series of redox-active molecules wherein each molecule bears a benzylphosphonic acid tether. The redox-active molecules include zinc porphyrins, a cobalt porphyrin, and a ferrocene-zinc porphyrin. An analogous tripodal tether has been prepared that is based on a tris[4-(dihydroxyphosphorylmethyl)phenyl]-derivatized methane. A zinc porphyrin is linked to the methane vertex by a 1,4-phenylene unit. The tripodal systems are designed to improve monolayer stability and ensure vertical orientation of the redox-active porphyrin on the electroactive surface. For comparison purposes, a zinc porphyrin bearing a hexylphosphonic acid tether also has been prepared. The synthetic approaches for introduction of the phosphonic acid group include derivatization of a bromoalkyl porphyrin or use of a dimethyl or diethyl phosphonate substituted precursor in a porphyrin-forming reaction. The latter approach makes use of dipyrromethane building blocks bearing mono or tripodal dialkyl phosphonate groups. The zinc porphyrin-tripodal compound bearing benzylphosphonic acid legs tethered to a SiO(2) surface (grown on doped Si) was electrically well-behaved and exhibited characteristic porphyrin oxidation/reduction waves. Collectively, a variety of porphyrinic molecules can now be prepared with tethers of different length, composition, and structure (mono or tripodal) for studies of molecular-based information storage on oxide surfaces.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Loewe, RS and Ambroise, A and Muthukumaran, K and Padmaja, K and Lysenko, AB and Mathur, G and Li, QL and Bocian, DF and Misra, V and Lindsey, JS}, year={2004}, month={Mar}, pages={1453–1460} }
 @article{yu_muthukumaran_sazanovich_kirmaier_hindin_diers_boyle_bocian_holten_lindsey_2003, title={Excited-state energy-transfer dynamics in self-assembled triads composed of two porphyrins and an intervening bis(dipyrrinato)metal complex}, volume={42}, ISSN={["1520-510X"]}, DOI={10.1021/ic034559m}, abstractNote={The synthesis and characterization of various triads composed of a linear array of two zinc porphyrins joined via an intervening bis(dipyrrinato)metal(II) complex are reported. The preparation exploits the facile complexation of dipyrrins with divalent metal ions to give bis(dipyrrinato)metal(II) complexes [abbreviated (dp)(2)M]. Copper(II) and palladium(II) chelates of dipyrrins (available by oxidation of dipyrromethanes) were prepared in 50-80% yield. A one-flask synthesis of bis(dipyrrinato)zinc(II) complexes was developed by oxidation of a dipyrromethane with DDQ or p-chloranil in the presence of Zn(OAc)(2).2H(2)O in THF ( approximately 80% yield). Three routes were developed for preparing porphyrin-dipyrrins: (1). Suzuki coupling of a boronate-substituted zinc porphyrin (ZnP) and bis[5-(4-iodophenyl)dipyrrinato]Pd(II) to give the (ZnP-dp)(2)Pd triad (50% yield), followed by selective demetalation of the (dp)(2)Pd unit by treatment with 1,4-dithiothreitol under neutral conditions (71% yield); (2). oxidation of a porphyrin-dipyrromethane with p-chloranil in the presence of Zn(OAc)(2).2H(2)O followed by chromatography on silica gel (71% yield); and (3). condensation of a dipyrrin-dipyrromethane and a dipyrromethane-dicarbinol under InCl(3) catalysis followed by oxidation with DDQ (10-16% yield). Four triads of form (ZnP-dp)(2)Zn were prepared in 83-97% yield by treatment of a porphyrin-dipyrrin with Zn(OAc)(2).2H(2)O at room temperature. Free base dipyrrins typically absorb at 430-440 nm, while the bis(dipyrrinato)metal complexes absorb at 460-490 nm. The fluorescence spectra/yields and excited-state lifetimes of the (ZnP-dp)(2)Zn triad in toluene show (1). efficient energy transfer from the bis(dipyrrinato)zinc(II) chromophore to the zinc porphyrins (98.5% yield), and (2). little or no quenching of the resulting excited zinc porphyrin relative to the isolated chromophore. Taken together, these results indicate that bis(dipyrrinato)zinc(II) complexes can serve as self-assembling linkers that further function as secondary light-collection elements in porphyrin-based light-harvesting arrays.}, number={21}, journal={INORGANIC CHEMISTRY}, author={Yu, LH and Muthukumaran, K and Sazanovich, IV and Kirmaier, C and Hindin, E and Diers, JR and Boyle, PD and Bocian, DF and Holten, D and Lindsey, JS}, year={2003}, month={Oct}, pages={6629–6647} }
 @article{sazanovich_balakumar_muthukumaran_hindin_kirmaier_diers_lindsey_bocian_holten_2003, title={Excited-state energy-transfer dynamics of self-assembled imine-linked porphyrin dyads}, volume={42}, ISSN={["1520-510X"]}, DOI={10.1021/ic034558u}, abstractNote={Toward the development of new strategies for the synthesis of multiporphyrin arrays, we have prepared and characterized (electrochemistry and static/time-resolved optical spectroscopy) a series of dyads composed of a zinc porphyrin and a free base porphyrin joined via imine-based linkers. One dyad contains two zinc porphyrins. Imine formation occurs under gentle conditions without alteration of the porphyrin metalation state. Five imine linkers were investigated by combination of formyl, benzaldehyde, and salicylaldehyde groups with aniline and benzoic hydrazide groups. The imine-linked dyads are quite stable to routine handling. The excited-state energy-transfer rate from zinc to free base porphyrin ranges from (70 ps)(-)(1) to (13 ps)(-)(1) in toluene at room temperature depending on the linker employed. The energy-transfer yield is generally very high (>97%), with low yields of deleterious hole/electron transfer. Collectively, this work provides the foundation for the design of multiporphyrin arrays that self-assemble via stable imine linkages, have predictable electronic properties, and have comparable or even enhanced energy-transfer characteristics relative to those of other types of covalently linked systems.}, number={21}, journal={INORGANIC CHEMISTRY}, author={Sazanovich, IV and Balakumar, A and Muthukumaran, K and Hindin, E and Kirmaier, C and Diers, JR and Lindsey, JS and Bocian, DF and Holten, D}, year={2003}, month={Oct}, pages={6616–6628} }