Synthesis of covalently linked linear porphyrin triad and tetrad containing different porphyrin sub-units

Covalently linked diarylethyne bridged unsymmetrical porphyrin triad containing ZnN4, N4, and N2S2 porphyrin sub-units and porphyrin tetrad containing ZnN4, N4, N3S, and N2S2 porphyrin sub-units were synthesized over sequence of Pd(0) mediated coupling reactions. The triad and tetrad are freely soluble in all common organic solvents and characterized by ES-MS, NMR, absorption, fluorescence, and electrochemical techniques. The 1H NMR, absorption, and electrochemical studies indicated a weak interaction between the porphyrin sub-units of porphyrin triad and porphyrin tetrad. The steady state and time-resolved fluorescence studies supported an energy transfer from one end of porphyrin array to the other end. This kind of porphyrin arrays containing different porphyrin sub-units will be useful for molecular electronics applications.© Elsevie

A simple route to prepare monofunctionalised 21-thia-, 21,23-dithia-, and 21-thia-23-oxaporphyrins from unsymmetrical thiophene diols and their use in the synthesis of covalently linked unsymmetrical porphyrin dimers

A series of unsymmetrical thiophene diols has been prepared in two steps from thiophene in 16-46% yields. The unsymmetrical thiophene diols containing functionalised aryl groups were then used as key synthons for the synthesis of a series of monofunctionalised 21-thia (N3S), 21,23-dithia (N2S2) and 21-thia-23-oxaporphyrins (N2SO). Condensation of one equivalent of unsymmetrical diol with either two equivalents of aldehyde and three equivalents of pyrrole, one equivalent of symmetrical 16-thiatripyrrane or one equivalent of symmetrical 16-oxatripyrrane under standard porphyrin-forming conditions resulted in monofunctionalised 21-thia-, 21,23-dithia- or 21-thia-23-oxaporphyrins in decent yields. This unsymmetrical diol method is simple, versatile and gives an access for the first time to any desired monofunctionalised porphyrins with N3S, N2S2 and N2SO porphyrin cores. The use of monofunctionalised N3S, N2S2 and N2SO porphyrins is further demonstrated by synthesising the first examples of three new covalently linked diarylethyne-bridged unsymmetrical dimers containing two different porphyrin cores such as N2S2-N-4, N2S2-N3S and N2S2-N2SO ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Synthesis of N3S, N3O, N2S2, N2O2, N2SO and N2OS porphyrins with one meso-unsubstituted carbon

A simple straightforward synthesis of N3S N2S2, N2O2, N2SO and N2OS porphyrins and an improved method for the synthesis of an N3O porphyrin with one meso-unsubstituted carbon atom are reported from readily available precursors. The reactivity of the meso-unsubstituted carbon atom was demonstrated by carrying out bromination followed by Heck coupling reactions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

meso-5-bromo-10,15,20-tiri(p-tolyl)-21-thiaporphyrin as a precursor for the synthesis of novel compounds

The synthesis of eight novel compounds with meso-5-bromo-10, 15,20-tri(p-tolyl)-21-thiaporphyrin as a key synthon under mild Pd-coupling conditions is reported. The title compound was prepared easily by treating the readily available 10,15,20-tri(p-tolyl)-21-thiaporphyrin with. N-bromosuccinimide at room temperature for 10 min. The use of the title compound was demonstrated by synthesizing 21-thiaporphyrin-based complex systems such as ethyne-bridged N3S-N3S dyad, phenylethyne-bridged N3S-N3O dyad, N3S-N2S2. dyad, meso-meso-linked ZnN4-N3S dyad and ZnN4-N3S-ZnN4 triad under mild Pd-mediated coupling conditions. The steady-state fluorescence studies indicated a possibility of an efficient energy transfer between the two porphyrin subunits in the dyads and triad. (C) Wiley-VCH Verlag GmbH & Co

First triazole-bridged unsymmetrical porphyrin dyad via click chemistry

[GRAPHICS] Click chemistry has been successfully applied in the synthesis of the first example of a triazole-bridged porphyrin dyad containing N2S2 porphyrin and N-4 or ZnN4 porphyrin subunits, and fluorescence study indicated a possibility of singlet-singlet energy transfer from the N-4 or ZnN4 porphyrin subunit to the N2S2 porphyrin subunit

Meso-5-Bromo-10,15,20-tris(p-tolyl)-21-thiaporphyrin as a precursor for the synthesis of novel compounds

The synthesis of eight novel compounds with meso-5-bromo-10,15,20-tri(p-tolyl)-21-thiaporphyrin as a key synthon under mild Pd-coupling conditions is reported. The title compound was prepared easily by treating the readily available 10,15,20-tri(p-tolyl)-21-thiaporphyrin with N-bromosuccinimide at room temperature for 10 min. The use of the title compound was demonstrated by synthesizing 21-thiaporphyrin-based complex systems such as ethyne-bridged N₃S-N₃S dyad, phenylethyne-bridged N₃S-N₃O dyad, N₃S-N₂S₂ dyad, meso-meso-linked ZnN₄-N₃S dyad and ZnN₄-N₃S-ZnN₄ triad under mild Pd-mediated coupling conditions. The steady-state fluorescence studies indicated a possibility of an efficient energy transfer between the two porphyrin subunits in the dyads and triad

Patterned Microfluidic Channels Using Self-assembled Hydroxy-Phenyl Porphyrin Monolayer

In order to achieve patterned surfaces for microfluidic applications, we show for the first time the use of self-assembled monolayer (SAM) of Hydroxy-phenyl porphyrin on SiO<SUB>2</SUB> surface following a chemical procedure. The SAM was characterized using ground state UV-absorption spectroscopy and H<SUB>2</SUB>O contact angle measurements. The UV-absorption spectra of the SAM exhibited a ~ 8 nm red shift in the Soret band compared to the porphyrin in toluene. This indicated the side-by-side orientation of the self assembled porphyrin molecules on SiO<SUB>2</SUB>. The molecular self-assembly is expected to be randomly oriented because of amorphous nature of the substrate. Sessile deionized (DI) water drop of 50 muL on SAM exhibited a contact angle of 75plusmn3. which is significantly higher than the contact angle of 33plusmn2. measured on the SiO<SUB>2</SUB> substrate. In this paper, we also demonstrate an approach of patterning the SiO<SUB>2</SUB> surface with the porphyrin SAM in order to achieve alternate hydrophobic/hydrophilic surfaces on a p-type device-quality (111) Si wafer. The application of such patterned surfaces is demonstrated with the help of microfluidic simulations study. A three-dimensional numerical simulation of flow in patterned microchannels with alternate layers of hydrophilic and hydrophobic surfaces at the bottom wall is studied here. Volume of fluid method (VOF) is used for simulating the free surface flow in the microchannel. Non-symmetric meniscus profiles with varying amplitude and shapes are obtained by changing the contact angles of the hydrophilic and hydrophobic surfaces. Flow instability is found to increase in the microchannels with patterned surfaces containing a variation in contact angles