@article{lysenko_thamyongkit_schmidt_diers_bocian_lindsey_2006, title={Diverse porphyrin dimers as candidates for high-density charge-storage molecules}, volume={10}, ISSN={["1099-1409"]}, DOI={10.1142/S1088424606000041}, abstractNote={ Porphyrinic molecules have been shown to be viable candidates for a molecular-based information storage medium on the basis of redox activity. An optimal redox-based information storage medium requires a large charge density in the molecular footprint on the anchoring substrate. The use of dimeric versus monomeric architectures affords one route to achieving increased charge density without sacrificing surface cross sectional area. Towards this goal, a series of zinc and cobalt containing porphyrin dimers has been prepared and characterized. The interporphyrin linkages in the dimers include p-phenylene, ethynyl, 1,4-butadiynyl, and ethynylphenylethynyl joining porphyrin meso-positions; Crossley-type fusion bridging porphyrin β-positions, and Osuka-type triple fusions bridging one meso- and two β-positions. The electrochemical features of each dimer have been evaluated. }, number={1}, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, author={Lysenko, Andrey B. and Thamyongkit, Patchanita and Schmidt, Izabela and Diers, James R. and Bocian, David F. and Lindsey, Jonathan S.}, year={2006}, pages={22–32} }
 @article{lysenko_malinovskii_padmaja_wei_diers_bocian_lindsey_2005, title={Multistate molecular information storage using S-acetylthio-derivatized dyads of triple-decker sandwich coordination compounds}, volume={9}, ISSN={["1099-1409"]}, DOI={10.1142/S1088424605000617}, abstractNote={An approach toward molecular information storage employs redox-active molecules attached to an electroactive surface. The chief advantages of such molecular capacitors include higher charge density and more versatile synthetic design than is afforded by typical semiconductor charge-storage materials. An architecture containing two triple-decker sandwich coordination complexes and an S-acetylthiomethyl-terminated tether has been designed for multibit storage. Each triple decker is composed of two phthalocyanines, one porphyrin, and two europium atoms. The oxidation potentials of each triple decker are tuned through the use of different substituents on the phthalocyanines (t-butyl, methyl, H ) and porphyrins (pentyl, p-tolyl). Interleaving of the four cationic oxidation states of each triple decker potentially affords eight distinct oxidation states. Two dyads were examined in solution and in self-assembled monolayers (SAMs) on a Au surface. One dyad exhibited eight distinct states in solution and in the SAM, thus constituting a molecular octal counter. The potentials ranged from −0.1-+1.3 V in solution and +0.1-+1.6 V in the SAM. Taken together, this approach provides a viable means of achieving multibit information storage at relatively low potential.}, number={7}, journal={JOURNAL OF PORPHYRINS AND PHTHALOCYANINES}, author={Lysenko, AB and Malinovskii, VL and Padmaja, K and Wei, LY and Diers, JR and Bocian, DF and Lindsey, JS}, year={2005}, pages={491–508} }
 @article{tomizaki_lysenko_taniguchi_lindsey_2004, title={Synthesis of phenylethyne-linked porphyrin dyads}, volume={60}, ISSN={["0040-4020"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-1042275557&partnerID=MN8TOARS}, DOI={10.1016/j.tet.2004.01.003}, abstractNote={Four new porphyrin dyads have been prepared for studies in artificial photosynthesis. The two porphyrins are joined at the meso positions via a phenylethyne linker and are present in zinc/zinc or zinc/free base metalation states. The porphyrin bearing the ethynyl unit incorporates zero, one, or two pentafluorophenyl groups at non-linking meso positions for tuning the porphyrin redox potentials. The synthetic approach entailed Pd-mediated coupling of porphyrin building blocks that bear a single ethynylphenyl or bromo/iodo substituent.}, number={9}, journal={TETRAHEDRON}, publisher={Elsevier BV}, author={Tomizaki, K and Lysenko, AB and Taniguchi, M and Lindsey, JS}, year={2004}, month={Feb}, pages={2011–2023} }
 @article{liu_yasseri_loewe_lysenko_malinovskii_zhao_surthi_li_misra_lindsey_et al._2004, title={Synthesis of porphyrins bearing hydrocarbon tethers and facile covalent attachment to Si(100)}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo049439q}, abstractNote={The use of redox-active molecules as the active storage elements in memory chips requires the ability to attach the molecules to an electroactive surface in a reliable and robust manner. To explore the use of porphyrins tethered to silicon via carbosilane linkages, 17 porphyrins have been synthesized. Fourteen porphyrins bear a tether at a single meso site, and three porphyrins bear functional groups at two beta sites for possible two-point attachment. Two high-temperature processing methods (400 degrees C under inert atmosphere) have been developed for rapid (minutes), facile covalent attachment to Si platforms. The high-temperature processing conditions afford attachment either by direct deposition of a dilute solution (1 microM-1 mM) of the porphyrin sample onto the Si substrate or sublimation of a neat sample onto the Si substrate. The availability of this diverse collection of porphyrins enables an in-depth examination of the effects of the tether (length, composition, terminal functional group, number of tethers) and steric bulk of nonlinking substituents on the information-storage properties of the porphyrin monolayers obtained upon attachment to silicon. Attachment proceeds readily with a wide variety of hydrocarbon tethers, including 2-(trimethylsilyl)ethynyl, vinyl, allyl, or 3-butenyl directly appended to the porphyrin and iodo, bromomethyl, 2-(trimethylsilyl)ethynyl, ethynyl, vinyl, or allyl appended to the 4-position of a meso-phenyl ring. No attachment occurs with substituents such as phenyl, p-tolyl, mesityl, or ethyl. Collectively, the studies show that the high-temperature attachment procedure (1) has broad scope encompassing diverse functional groups, (2) tolerates a variety of arene substituents, and (3) does not afford indiscriminate attachment. The high-temperature processing conditions are ideally suited for use in fabrication of hybrid molecular/semiconductor circuitry.}, number={17}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Liu, ZM and Yasseri, AA and Loewe, RS and Lysenko, AB and Malinovskii, VL and Zhao, Q and Surthi, S and Li, QL and Misra, V and Lindsey, JS and et al.}, year={2004}, month={Aug}, pages={5568–5577} }
 @article{balakumar_lysenko_carcel_malinovskii_gryko_schweikart_loewe_yasseri_liu_bocian_et al._2004, title={Diverse redox-active molecules bearing O-, S-, or Se-terminated tethers for attachment to silicon in studies of molecular information storage}, volume={69}, ISSN={["1520-6904"]}, DOI={10.1021/jo034944t}, abstractNote={A molecular approach to information storage employs redox-active molecules tethered to an electroactive surface. Attachment of the molecules to electroactive surfaces requires control over the nature of the tether (linker and surface attachment group). We have synthesized a collection of redox-active molecules bearing different linkers and surface anchor groups in free or protected form (hydroxy, mercapto, S-acetylthio, and Se-acetylseleno) for attachment to surfaces such as silicon, germanium, and gold. The molecules exhibit a number of cationic oxidation states, including one (ferrocene), two [zinc(II)porphyrin], three [cobalt(II)porphyrin], or four (lanthanide triple-decker sandwich compound). Electrochemical studies of monolayers of a variety of the redox-active molecules attached to Si(100) electrodes indicate that molecules exhibit a regular mode of attachment (via a Si-X bond, X = O, S, or Se), relatively homogeneous surface organization, and robust reversible electrochemical behavior. The acetyl protecting group undergoes cleavage during the surface deposition process, enabling attachment to silicon via thio or seleno groups without handling free thiols or selenols.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Balakumar, A and Lysenko, AB and Carcel, C and Malinovskii, VL and Gryko, DT and Schweikart, KH and Loewe, RS and Yasseri, AA and Liu, ZM and Bocian, DF and et al.}, year={2004}, month={Mar}, pages={1435–1443} }
 @article{wei_padmaja_youngblood_lysenko_lindsey_bocian_2004, title={Diverse redox-active molecules bearing identical thiol-terminated tripodal tethers for studies of molecular information storage}, volume={69}, ISSN={["0022-3263"]}, DOI={10.1021/jo0349476}, abstractNote={To examine the effects of molecular structure on charge storage in self-assembled monolayers (SAMs), a family of redox-active molecules has been prepared wherein each molecule bears a tether composed of a tripodal linker with three protected thiol groups for surface attachment. The redox-active molecules include ferrocene, zinc porphyrin, ferrocene-zinc porphyrin, magnesium phthalocyanine, and triple-decker lanthanide sandwich coordination compounds. The tripodal tether is based on a tris[4-(S-acetylthiomethyl)phenyl]-derivatized methane. Each redox-active unit is linked to the methane vertex by a 4,4'-diphenylethyne unit. The electrochemical characteristics of each compound were examined in solution and in SAMs on Au. Redox-kinetic measurements were also performed on the SAMs (with the exception of the magnesium phthalocyanine) to probe (1) the rate of electron transfer in the presence of an applied potential and (2) the rate of charge dissipation after the applied potential is disconnected. The electrochemical studies of the SAMs indicate that the tripodal tether provides a more robust anchor to the Au surface than does a tether with a single site of attachment. However, the electron-transfer and charge-dissipation characteristics of the two tethers are generally similar. These results suggest that the tripodal tether offers superior stability characteristics without sacrificing electrochemical performance.}, number={5}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Wei, LY and Padmaja, K and Youngblood, WJ and Lysenko, AB and Lindsey, JS and Bocian, DF}, year={2004}, month={Mar}, pages={1461–1469} }
 @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{schweikart_malinovskii_yasseri_li_lysenko_bocian_lindsey_2003, title={Synthesis and characterization of bis(S-acetylthio)-derivatized europium triple-decker monomers and oligomers}, volume={42}, ISSN={["0020-1669"]}, DOI={10.1021/ic034730u}, abstractNote={We report the synthesis of monomers, dimers, trimers, and oligomers of triple-decker (TD) complexes bearing S-acetylthio groups at the termini: AcS-(TD)(n)()-SAc. Each TD was of type (Pc)Eu(Pc)Eu(Por), where H(2)Pc = tetra-tert-butylphthalocyanine and H(2)Por is a meso-tetraarylporphyrin bearing functional groups at the 4-aryl position such as ethynyl, TMS-ethynyl, TIPS-ethynyl, or iodo. The TD arrays were prepared by Sonogashira- and Glaser-type coupling reactions, affording 1,4-diphenylethyne or 1,4-diphenylbutadiyne linkers joining the TDs. Each TD array exhibited high solubility in organic solvents such as CHCl(3) or CH(2)Cl(2). Self-assembled monolayers (SAMs) of all the TDs were prepared on Au substrates and investigated via a variety of electrochemical techniques aimed at determining redox potentials, rates of electron transfer under applied potential, and rates of charge retention in the absence of applied potential. The electrochemical measurements were accompanied by ellipsometric studies aimed at determining SAM thickness and, hence, the orientation of the complexes with respect to the surface plane. All of the TD SAMs exhibit robust, reversible voltammetry yielding four well-resolved waves in the potential range of 0 to +1.6 V (corresponding to the mono-, di-, tri-, and tetracations). The electron-transfer rates for the various oxidation states of all of the TD SAMS are similar and in the 10(4)-10(5) s(-)(1) range. The charge-dissipation rates (measured in terms of a charge-retention half-life) are also similar and are in the 10-60 s range. These rates are influenced by both the packing density of the molecules and the orientation of the molecules on the surface. The full body of data supports the view that all of the dithio-derivatized TD complexes assume a similar geometry on the surface. In particular, the complexes are oriented with their linkers/macrocycle planes generally parallel with the surface, unlike monothio-derivatized analogues, which are in a more perpendicular geometry. The parallel geometry of the dithio-derivatized TDs is qualitatively consistent with covalent attachment to Au via both thiols.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Schweikart, KH and Malinovskii, VL and Yasseri, AA and Li, JZ and Lysenko, AB and Bocian, DF and Lindsey, JS}, year={2003}, month={Nov}, pages={7431–7446} }