@article{ambroise_kirmaier_wagner_loewe_bocian_holten_lindsey_2002, title={Weakly coupled molecular photonic wires: Synthesis and excited-state energy-transfer dynamics}, volume={67}, ISSN={["1520-6904"]}, DOI={10.1021/jo025561i}, abstractNote={Molecular photonic wires, which absorb light and undergo excited-state energy transfer, are of interest as biomimetic models for photosynthetic light-harvesting systems and as molecular devices with potential applications in materials chemistry. We describe the stepwise synthesis of four molecular photonic wires. Each wire consists of an input unit, transmission element, and output unit. The input unit consists of a boron-dipyrrin dye or a perylene-monoimide dye (linked either at the N-imide or the C9 position); the transmission element consists of one or three zinc porphyrins affording short or long wires, respectively; and the output unit consists of a free base (Fb) porphyrin. The components in the arrays are joined in a linear architecture via diarylethyne linkers (an ethynylphenyl linker is attached to the C9-linked perylene). The wires have been examined by static absorption, static fluorescence, and time-resolved absorption spectroscopy. Each wire (with the exception of the C9-linked perylene wire) exhibits a visible absorption spectrum that is the sum of the spectra of the component parts, indicating the relatively weak electronic coupling between the components. Excitation of each wire at the wavelength where the input unit absorbs preferentially (typically 480-520 nm) results in emission almost exclusively from the Fb porphyrin. The static emission and time-resolved data indicate that the overall rate constants and quantum efficiencies for end-to-end (i.e., input to output) energy transfer are as follows: perylene-(N-imide)-linked short wire, (33 ps)(-1) and >99%; perylene-(C9)-linked short wire, (26 ps)(-1) and >99%; boron-dipyrrin-based long wire, (190 ps)(-1) and 81%; perylene-(N-imide)-linked long wire, (175 ps)(-1) and 86%. Collectively, the studies provide valuable insight into the singlet-singlet excited-state energy-transfer properties in weakly coupled molecular photonic wires.}, number={11}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Ambroise, A and Kirmaier, C and Wagner, RW and Loewe, RS and Bocian, DF and Holten, D and Lindsey, JS}, year={2002}, month={May}, pages={3811–3826} }
 @article{ambroise_wagner_rao_riggs_hascoat_diers_seth_lammi_bocian_holten_et al._2001, title={Design and synthesis of porphyrin-based optoelectronic gates}, volume={13}, ISSN={["1520-5002"]}, DOI={10.1021/cm000773m}, abstractNote={Two porphyrin-based optoelectronic gates and several prototypical redox-switching components of gates have been synthesized for studies in molecular photonics. Linear and T-shaped molecular optoelectronic gates contain a boron-dipyrrin (BDPY) dye as the input unit, a zinc (Zn) porphyrin as the transmission unit, a free base (Fb) porphyrin as the output unit, and a magnesium (Mg) porphyrin as the redox-switching unit. The linear gate and T gate were synthesized using a molecular building block approach. In the linear gate synthesis, a BDPY−Zn porphyrin dyad was coupled with a Fb porphyrin−Mg porphyrin dimer. The synthesis of the T gate utilized a Zn porphyrin bearing four different meso substituents:  mesityl, 4-iodophenyl, 4-[2-(trimethylsilyl)ethynyl]phenyl, and 4-[2-triisopropyl)ethynyl]phenyl. Attachment of the three different groups to the Zn porphyrin was accomplished using successive Pd-mediated coupling reactions in the following sequence:  Fb porphyrin (output unit), BDPY dye (input unit), and Mg ...}, number={3}, journal={CHEMISTRY OF MATERIALS}, author={Ambroise, A and Wagner, RW and Rao, PD and Riggs, JA and Hascoat, P and Diers, JR and Seth, J and Lammi, RK and Bocian, DF and Holten, D and et al.}, year={2001}, month={Mar}, pages={1023–1034} }
 @article{lammi_wagner_ambroise_diers_bocian_holten_lindsey_2001, title={Mechanisms of excited-state energy-transfer gating in linear versus branched multiporphyrin arrays}, volume={105}, ISSN={["1520-5207"]}, DOI={10.1021/jp010857y}, abstractNote={We have investigated electrochemical switching of excited-state electronic energy migration in two optoelectronic gates with different architectures. Each gate consists of diarylethyne-linked subunits:  a boron-dipyrrin (BDPY) input unit, a Zn-porphyrin transmission unit, a free-base-porphyrin (Fb-porphyrin) output unit, and a Mg-porphyrin redox-switched site connected either to the Fb porphyrin (linear gate) or to the Zn porphyrin (branched, T gate). Both the linear and branched architectures show Fb-porphyrin emission when the Mg porphyrin is neutral and nearly complete quenching when the Mg porphyrin is oxidized to the π-cation radical. To determine the mechanism of gating, we undertook a systematic photophysical study of the gates and their dyad and triad components in neutral and oxidized forms, using static and time-resolved optical spectroscopy. Two types of photoinduced energy-transfer (and/or charge-transfer) processes are involved in gate operation:  transfer between adjacent subunits and transf...}, number={22}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Lammi, RK and Wagner, RW and Ambroise, A and Diers, JR and Bocian, DF and Holten, D and Lindsey, JS}, year={2001}, month={Jun}, pages={5341–5352} }
 @article{lammi_ambroise_wagner_diers_bocian_holten_lindsey_2001, title={Quenching of porphyrin excited states by adjacent or distant porphyrin cation radicals in molecular arrays}, volume={341}, ISSN={["0009-2614"]}, DOI={10.1016/S0009-2614(01)00452-3}, abstractNote={The quenching of photoexcited porphyrins by porphyrin cation radicals at adjacent or distant sites in diphenylethyne-linked porphyrin dyads and triads has been studied using static and time-resolved optical spectroscopy. The excited-state quenching is highly efficient in all cases (>99%) and occurs in ⩽11 ps between adjacent sites (by through-bond energy/charge transfer) and in ⩽55 ps between distant sites (likely by superexchange-assisted energy transfer). The rates can be tuned using the porphyrin-linker connection motif. These results should prove useful in the design of arrays that use electro- or photo-chemically generated porphyrin cation radicals for molecular switching and other applications in molecular photonics.}, number={1-2}, journal={CHEMICAL PHYSICS LETTERS}, author={Lammi, RK and Ambroise, A and Wagner, RW and Diers, JR and Bocian, DF and Holten, D and Lindsey, JS}, year={2001}, month={Jun}, pages={35–44} }
 @article{lammi_ambroise_balasubramanian_wagner_bocian_holten_lindsey_2000, title={Structural control of photoinduced energy transfer between adjacent and distant sites in multiporphyrin arrays}, volume={122}, ISSN={["0002-7863"]}, DOI={10.1021/ja001031x}, abstractNote={A family of diphenylethyne-linked porphyrin dimers and trimers has been prepared via a building block approach for studies of energy-transfer processes. The dimers contain Mg and Zn porphyrins (MgZnU); the trimers contain an additional free base porphyrin (MgZnFbU). In both the dimers and trimers, sites of attachment to the Mg porphyrin (at the meso- or β-position) and diphenylethyne linker (at the para- or meta-positions) were varied, producing four Mg porphyrin−Zn porphyrin arrangements with the following linker configurations:  meso-p/p-meso, meso-m/p-meso, β-p/p-meso, and β-m/p-meso. All four trimers employ a meso-p/p-meso Zn porphyrin−Fb porphyrin connection. The ground- and excited-state properties of the porphyrin dimers and trimers have been examined using static and time-resolved optical techniques. The rate of energy transfer from the photoexcited Zn porphyrin to the Mg porphyrin decreases according to the following trend:  meso-p/p-meso (9 ps)-1 > β-p/p-meso (14 ps)-1 > meso-m/p-meso (19 ps)-1 ...}, number={31}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Lammi, RK and Ambroise, A and Balasubramanian, T and Wagner, RW and Bocian, DF and Holten, D and Lindsey, JS}, year={2000}, month={Aug}, pages={7579–7591} }
 @article{wagner_ciringh_clausen_lindsey_1999, title={Investigation and refinement of palladium-coupling conditions for the synthesis of diarylethyne-linked multiporphyrin arrays}, volume={11}, ISSN={["0897-4756"]}, DOI={10.1021/cm9903529}, abstractNote={The synthesis of diarylethyne-linked multiporphyrin arrays requires Pd-mediated coupling conditions that are performed in dilute solution in the absence of copper and that give reaction mixtures that are easily purified. We previously developed copper-free Pd-mediated coupling conditions (Pd2(dba)3 and AsPh3 in toluene/triethylamine (5:1) at 35 °C) but extensive chromatography was required to remove unidentified porphyrinic byproducts. We have used laser-desorption mass spectrometry (LD-MS) and analytical size-exclusion chromatography (SEC) to assay the products from the coupling reaction of a zinc(II) iodophenylporphyrin (ZnI) and a zinc(II) ethynylphenylporphyrin (ZnU‘). Analysis of the crude reaction mixture revealed the diphenylethyne-linked dimer (Zn2U) as the major product, byproducts plausibly derived from phenyl−aryl exchange processes (a phenylated derivative of ZnU‘, a Ph2As-substituted derivative of ZnI), byproducts believed to originate from direct phenylation processes (a phenylated derivativ...}, number={10}, journal={CHEMISTRY OF MATERIALS}, author={Wagner, RW and Ciringh, Y and Clausen, C and Lindsey, JS}, year={1999}, month={Oct}, pages={2974–2983} }
 @article{wagner_li_du_lindsey_1999, title={Investigation of cocatalysis conditions using an automated microscale multireactor workstation: Synthesis of meso-tetramesitylporphypin}, volume={3}, ISSN={["1083-6160"]}, DOI={10.1021/op9800459}, abstractNote={Prior manual work has shown that the condensation of mesitaldehyde and pyrrole leading to tetramesitylporphyrin depends sensitively on concentration and requires cocatalysis involving BF3·O(Et)2 and ethanol or other protic species. We have applied an automated microscale chemistry workstation capable of parallel or adaptive experimentation to systematically investigate these cocatalysis conditions. Examination of experimental grids spanning a 1000-fold range of the concentrations of BF3·O(Et)2 and ethanol identified the best cocatalysis conditions for various mesitaldehyde and pyrrole concentrations. As the reaction concentration increased from 10 to 200 mM, the optimal yields were achieved with a parallel increase in BF3·O(Et)2 concentration (from 3.3 to 56 mM), but the amount of ethanol remained relatively constant. Catalysis conditions were identified that afforded ∼30% yields for reactants in the range of 10−73 mM, thereby enabling the reaction to be performed at increased concentration without loss i...}, number={1}, journal={ORGANIC PROCESS RESEARCH & DEVELOPMENT}, author={Wagner, RW and Li, FR and Du, H and Lindsey, JS}, year={1999}, pages={28–37} }
 @article{littler_miller_hung_wagner_df o'shea_boyle_lindsey_1999, title={Refined synthesis of 5-substituted dipyrromethanes}, volume={64}, ISSN={["0022-3263"]}, DOI={10.1021/jo982015+}, abstractNote={5-Substituted dipyrromethanes are important precursors for the synthesis of meso-substituted porphyrins,1 expanded porphyrins, and porphyrin analogues.2 Several one-flask methods have been reported for the synthesis of 5-substituted dipyrromethanes by the condensation of an aldehyde and pyrrole using various combinations of acids and solvents.3-14 We previously reported a one-flask synthesis of dipyrromethanes in which an aldehyde is dissolved in a 40-fold excess of pyrrole with a catalytic amount of an acid at room temperature in the absence of any other solvent.8 This method has afforded good yields of 5-substituted dipyrromethanes bearing many types of functional groups.15 However, purification of the product is typically achieved by flash column chromatography, restricting application to the small-scale preparation of dipyrromethanes. Our objective in this study was to eliminate the use of chromatography during purification, thereby removing the major bottleneck to the synthesis of multigram quantities of dipyrromethanes. Upon examining the crude reaction mixture from the acid-catalyzed condensation of benzaldehyde in excess pyrrole, we found that the principal reaction products consist of the dipyrromethane (1), the N-confused dipyrromethane (2,3′-dipyrromethane) (2) and the tripyrrane (3) (Scheme 1). The presence of the N-confused dipyrromethane was surprising as this species had not been detected previously.8 Using GC we have examined the distribution of these products as a function of the pyrrole:benzaldehyde ratio and the acid catalyst. We have developed a purification process based on bulb-to-bulb distillation followed by recrystallization that affords analytically pure dipyrromethanes in multigram quantities. The condensation of pyrrole and benzaldehyde upon heating without added acids has also been examined.}, number={4}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Littler, BJ and Miller, MA and Hung, CH and Wagner, RW and DF O'Shea and Boyle, PD and Lindsey, JS}, year={1999}, month={Feb}, pages={1391–1396} }
 @article{wagner_seth_yang_kim_bocian_holten_lindsey_1998, title={Synthesis and excited-state photodynamics of a molecular square containing four mutually coplanar porphyrins}, volume={63}, ISSN={["0022-3263"]}, DOI={10.1021/jo9803683}, abstractNote={To examine the effect of restricted porphyrin−porphyrin rotation on energy transfer in diphenylethyne-linked porphyrin arrays, a square macrocyclic array of four porphyrins has been prepared that locks the porphyrins in a mutually coplanar architecture. The palladium-mediated coupling of Zn(II) 5,10-dimesityl-15,20-bis(4-ethynylphenyl)porphyrin and 5,10-dimesityl-15,20-bis(4-iodophenyl)porphyrin afforded the molecular square (cyclo-Zn2Fb2U) with zinc (Zn) and free base (Fb) porphyrins on alternating corners. The yield of cyclo-Zn2Fb2U is relatively insensitive to concentration with reactants at 5−0.5 mM but declines significantly at ≤0.05 mM. Transient absorption data from cyclo-Zn2Fb2U in toluene at room temperature indicate that the rate of energy transfer from the photoexcited Zn porphyrin to a neighboring Fb porphyrin is (26 ps)-1. A ZnFb porphyrin (ZnFbU) with an identical diphenylethyne linker but no constraints on rotation exhibits an identical energy-transfer rate. Resonance Raman spectroscopy sho...}, number={15}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Wagner, RW and Seth, J and Yang, SI and Kim, D and Bocian, DF and Holten, D and Lindsey, JS}, year={1998}, month={Jul}, pages={5042–5049} }
 @article{wagner_johnson_lindsey_1997, title={Investigation of the one-flask synthesis of porphyrins bearing meso-linked straps of variable length, rigidity, and redox activity}, volume={53}, ISSN={["0040-4020"]}, DOI={10.1016/S0040-4020(97)00327-X}, abstractNote={The reactions of 18 dialdehydes have been examined in the two-step one-flask room temperature porphyrin synthesis. Efficient alkylation methods were established for the reaction of diols and diacids with m-bromomethylbenzaldehyde. Dialdehydes linked at the o,o′-or m,m′-positions were converted to strapped porphyrins in yields up to 25%, while the one p,p′-linked dialdehyde that was examined failed to give porphyrin. The resulting porphyrins bear straps joining adjacent meso-positions rather than across the face of the porphyrin. Dialdehydes incorporating rigid groups provided improved yields in some but not all cases. The yield of strapped porphyrin exhibited a maximum at 10−2 M reactant concentrations. The o,o′-strapped porphyrins exist as atropisomers that are sufficiently stable to interconversion at room temperature to be separable chromatographically. No atropisomers of m,m′-strapped porphyrins could be separated, though some could be observed by 1H NMR spectroscopy. For two different m,m′-strapped porphyrins, the ΔG‡ values for interconversion of the atropisomers were found to be 66 and 68 kJ/mol. The outer rings in these strapped porphyrins range in size from 14 to 24 atoms. Five porphyrins with bridging redox-active groups (ferrocene or anthraquinone) have been prepared in one-flask reactions, including a porphyrin bearing one ferrocene and one anthraquinone in straps across adjacent meta-substituted phenyl sites.}, number={20}, journal={TETRAHEDRON}, author={Wagner, RW and Johnson, TE and Lindsey, JS}, year={1997}, month={May}, pages={6755–6790} }
 @article{wagner_lindsey_1996, title={Boron-dipyrromethene dyes for incorporation in synthetic multi-pigment light-harvesting arrays}, volume={68}, ISSN={["0033-4545"]}, DOI={10.1351/pac199668071373}, abstractNote={Abstract}, number={7}, journal={PURE AND APPLIED CHEMISTRY}, author={Wagner, RW and Lindsey, JS}, year={1996}, month={Jul}, pages={1373–1380} }
 @misc{wagner_johnson_lindsey_1996, title={Soluble synthetic multiporphyrin arrays .1. Modular design and synthesis}, volume={118}, ISSN={["0002-7863"]}, DOI={10.1021/ja961611n}, abstractNote={A set of porphyrin building blocks has been developed for the construction of light-harvesting model compounds and related molecular photonic devices. The porphyrins are facially encumbered to enhance solubility in organic solvents, are employed in a defined metalation state (free base (Fb) or zinc chelate), and bear peripheral functional groups such as iodo or ethyne for joining the porphyrins via covalent bonds. The coupling of an iodophenylporphyrin and an ethynylphenylporphyrin via mild Pd-mediated reactions (2−4 mM of each porphyrin in toluene/triethylamine (5:1) with Pd2(dba)3 and AsPh3 at 35 °C for 2 h) yields the corresponding diphenylethyne-linked multiporphyrin array in 70−80% yield. The arrays are easily purified by a sequence of flash silica chromatography, preparative size exclusion chromatography, and gravity elution silica chromatography. The diphenylethyne linkers give a center-to-center separation of the porphyrins of ∼20 A. Model light-harvesting compounds are easily prepared using Zn an...}, number={45}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Wagner, RW and Johnson, TE and Lindsey, JS}, year={1996}, month={Nov}, pages={11166–11180} }
 @article{hsiao_krueger_wagner_johnson_delaney_mauzerall_fleming_lindsey_bocian_donohoe_1996, title={Soluble synthetic multiporphyrin arrays .2. Photodynamics of energy-transfer processes}, volume={118}, ISSN={["0002-7863"]}, DOI={10.1021/ja961612f}, abstractNote={Soluble ethyne-linked tetraarylporphyrin arrays that mimic natural light-harvesting complexes by absorbing light and directing excited-state energy have been investigated by static and time-resolved absorption and fluorescence spectroscopies. Of particular interest is the role of the diarylethyne linkers in mediating energy transfer. The major conclusions from this study, which is limited to the examination of arrays containing Zn and free-base (Fb) porphyrins, include the following:  (1) Singlet excited-state energy transfer from the Zn porphyrin to the Fb porphyrin is extremely efficient (95−99%). Competitive electron-transfer reactions are not observed. (2) The rate of energy transfer is slowed up to 4-fold by the addition of groups to the linker that limit the ability of the linker and porphyrin to adopt geometries tending toward coplanarity. Thus, the mechanism of energy transfer predominantly involves through-bond communication via the linker. Consistent with this notion, the measured lifetimes of t...}, number={45}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Hsiao, JS and Krueger, BP and Wagner, RW and Johnson, TE and Delaney, JK and Mauzerall, DC and Fleming, GR and Lindsey, JS and Bocian, DF and Donohoe, RJ}, year={1996}, month={Nov}, pages={11181–11193} }