Stabilization of Charge-Separated States in Phthalocyanine−Fullerene Ensembles through Supramolecular Donor−Acceptor Interactions

Abstract

A novel ZnPc-C60 dyad (3), in which two photoactive units are brought together by a phenylenevinylene spacer has been synthesized. The synthetic strategy en route toward 3 involves a Heck reaction to attach 4-vinylbenzaldehyde to a monoiodophthalocyanine precursor, followed by standard cycloaddition of azomethine ylides (generated from the formylPc derivative and N-methylglycine) to one of the double bonds of C60. Electrochemical studies reveal that in 3 the ZnPc is about 39 mV more difficult to oxidize than in the corresponding ZnPc reference, which points to appreciable electronic communication between ZnPc and C60 in the ground state. In the excited state, photoexcitation leads to the formation of a charge-separated ZnPc*+-C60*- state, for which a lifetime of 130 ns was determined in THF. Hetero-association between complementary Pcs (1 and 2 or 3 and 2), which carry different peripheral functionalities (i.e., either electron-donating alkoxy groups or electron-deficient alkylsulfonyl chains) was assessed by different techniques. They provided evidence for donor-acceptor 1:1 complex formation with a stability constant of ca. 10(5) M(-1) in CHCl3. Interestingly, hetero-association of ZnPc-C60 dyad 3 with an electron-deficient PdPc (2) allowed the construction of supramolecular triads, in which a substantial stabilization of the radical pair is seen relative to that of the covalently linked dyad ZnPc-C60 (3).

Synthesis and spectroscopic investigation of trifluoroethoxy-coated phthalocyanine linked with fullerene

“…It is reported that the trifluoroethoxy groups of similar unsymmetrical phthalocyanines serve electron donor groups in a conjugated donor-acceptor dyad system [20]. In addition to this, fullerene always acts as an electron acceptor in fullerene dyad systems such as phthalocyanine-fullerene dyads [4][5][6][7][8][9][10][11][12][13], porphyrine-fullerene dyads [2,3] and perylene-fullerene dyads [21]. It is interested to note that fullerene does not serve an electron acceptor substituent in our donor-acceptor dyad 2.…”

“…Since then, interest in covalently bound fullerene-functionalized phthalocyanines has been increasing. Nowadays, several unsymmetrical metal phthalocyanine-fullerene conjugates via a flexible [5,6] or rigid [7][8][9][10][11][12][13] linker have been synthesized to study intramolecular processes such as electron and energy transfers between phthalocyanines and fullerenes. We recently disclosed a novel unsymmetrical metal phthalocyanine-fullerene dyad 1 for the development of thin film solar cells, in which fullerene is covalently bonded to a terminal position of phthalocyanine via a saturated alkyl chain.…”

Fabrication of Nickel Tetrasulfonated Phthalocyanine Functionalized Multiwalled Carbon Nanotubes on Activated Glassy Carbon Electrode for the Detection of Dopamine

“…Several positively charged polymers, such as poly allylamine, polydiphenylamine, polyaniline, poly propyleneimine, dioctadecyldimethylammonium bromide and polypyrrole have been utilized for the preparation of stable NiTsPc electrodes through electrostatic interaction between positively charged polymers and negatively charged NiTsPc [8,[18][19][20][21]. Engstrom and coworkers reported that anodically activated glassy carbon electrode (AGCE) have exhibited with increased electrochemical activity over freshly polished GCE [22].…”

Novel Electron Donor Acceptor Nanocomposites

“…As donors a wide variety of chromophores including porphyrins [35][36][37][38][39][40][41][42][43][44][45], phthalocyanines [46,47], amines [48], polycondensed aromatics [49], transition complexes [50][51][52], carotenoids [53], ferrocenes [54,55], tetrathiafulvalenes (TTF) [56], and others [57] have been employed. Here the photodynamics of zinc porphyrin-C 60 linked dyad 1 is presented to understand the typical relaxation processes of the excited states in donor-fullerene linked dyads (Figure 4.1) [37].…”