Excited-State Energy-Transfer Dynamics of Self-Assembled Imine-Linked Porphyrin Dyads

Abstract

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.

Design and Photophysical Properties of Zinc(II) Porphyrin‐Containing Dendrons Linked to a Central Artificial Special Pair

“…Complex 10 gave satisfactory mass spectral analysis. Mesityl-substituted AB 3 -porphyrin was chosen as the peripheral building block due to its favorable solubilizing properties and easy synthesis, [11] but this bulky group also prevents porphyrin aggregation and singlet-singlet annihilation (see below). The AB 3 -porphyrin can be prepared through a MacDonald condensation of mesityldipyrromethane [12] with mesitaldehyde and 4-acetamidobenzaldehyde under Lindsey conditions (Scheme 5).…”

“…The AB 3 -porphyrin can be prepared through a MacDonald condensation of mesityldipyrromethane [12] with mesitaldehyde and 4-acetamidobenzaldehyde under Lindsey conditions (Scheme 5). Hydrolysis of porphyrin amide 11 with HCl/ TFA at 80 8C [11] gave porphyrin amine 12, which was then acylated with glutaric anhydride to give compound 13 in quantitative yield. Activated ester 14 was prepared by condensation of this carboxylic acid derivative with N-hydroxysuccinimide in the presence of dicyclohexyl-…”

“…4,5-BisA C H T U N G T R E N N U N G [bis(4-ethyl-3-methyl-2-pyrryl)methyl]-9,9-dimethylxanthene (3), [6a] 4-(azidomethyl)benzaldehyde (5), [8] 3,4-dimethyl-1H-pyrrole-2-carbonic acid-tert-butyl ester, [48] N,N-bis(trifluoroacetyl)-1,7-diamino-4-azaheptane (16), [14] N-(tert-butoxycarbonyl)-1,7-diamino-4-azaheptane (20), [14] 5-mesityldipyrromethane, [12b] 5-(4-aminophenyl)-10,15,20-trimesitylporphyrin (12), [11] and 3-(trimethylsilyl)propargyl bromide [16] were synthesized as previously described.…”

Electronic and conformational features of derivatives of meso- thien-2-ylporphyrins on protonation and perbromination

“…In these compounds, there is a limitation in extending the ring conjugation effectively through the meso-position as the phenyl group is bulky and is nearly at an orthogonal disposition to the central porphyrin macrocycle (hereafter called core). For example, the electron withdrawing nature of aldehydic group has more effect on redox potentials when it is attached directly to the meso-position than on the phenyl ring at meso-position [6]. This limitation is generally overcome either by appending the groups of interest at the pyrrole b-position [7] or by using spacer like ethenyl at the meso-position [8][9][10][11] which will favour the conjugation between the aryl group and the core.…”

Applicability of 2-Hydroxybenzaldehyde Benzoylhydrazone in the Determination of Trace metals by Adsorptive Cathodic Stripping Voltammetry: Relevancy of Simultaneous Determinations

“…benzoylhydrazone (2-HBBH). This reagent was selected because it is one of the important Schiff bases; it can react with a large variety of transition metal cations [11][12][13] and can form numerous complexes. Different metals such as Cu(II), Pb(II), Cd(II) and Bi(III) produced electrochemical signals using 2-HBBH by AdCSV.…”