Facing facts: Coordination of Cp*Ru (Cp*=C(5)Me(5)) to the concave and convex π surfaces of subphthalocyanines constitutes a new approach to the functionalization of subazaporphyrins. While the convex face shows higher reactivity, coordination to the concave side produces a stronger diatropic influence on the Cp* ligand and a greater perturbation of the macrocyclic π-electronic features.
Three and six ferrocenyl subunits have been attached to the periphery of subphthalocyanines (SubPcs). Unlike axially coordinated ferrocenes, peripherally-bonded ferrocenes have an impact on the electronic features of SubPcs, which show a 44 to 70 nm red-shift of their Q-bands. The unusually deep and narrow ferrocenyl-SubPc is able to host C, giving rise to atypical SubPc•C cocrystallates, through a combination of concave-convex and convex-convex π-π interactions.
The electronic features of Zn(II) and Ru(II) phthalocyanines (Pcs) have been modulated by direct peripheral attachment of up to eight ferrocenes. The presence of peripheral ferrocenes noticeably impacts the electronic properties of the corresponding ZnPc and RuPc complexes 7, 12 and 9, 15, respectively-a notion that is supported by optical spectroscopy with bathochromic shifts of up to 8-10 nm per ferrocene unit. Cyclic voltammetry and optical spectroscopy reveal long-distance (10-11 bonds) electronic interaction between ferrocene units. The ZnPc and RuPc complexes have been integrated into a series of orthogonal, supramolecular bis(phthalocyanine)-perylenediimide electron donor-acceptor conjugates, 2a,b and 3a,b. In these cart-wheel-shaped arrays, coordination of ditopic perylenediimide 16, containing two pyridyl substituents at its imido positions, enabled selective interactions with the metal centers of phthalocyanines 7, 12, 9, and 15. The presence of ferrocenes in, for example, Zn complexes 2a and 3a triggers a fast energy transfer from the excited-state PDI to ZnPc. In the RuPc-PDI conjugates, substitution with ferrocenes produces a slight acceleration of the charge separation upon photoexcitation of the PDI chromophore. However, charge recombination is accelerated by 2 orders of magnitude in ferrocene-containing conjugates when compared to that in the analogous tert-butyl-substituted array 1b.
We have prepared two different subphthalocyanine conjugates by linking these macrocycles either to an electron-accepting perylene diimide or to an electron-donating phenothiazine through a single B-N covalent bond. The short spacing between the two active building blocks results in ultrafast photoinduced electron-transfer reactions.
A series of five push-pull porphyrazines of A B type, in which unit B is an isoindole 4-carboxylic acid, has been prepared. The units A have been endowed with thioether, amine, ether and alkyl functions, either directly attached to the β-position of the pyrrolic units, or connected to the porphyrazine core through p-substituted phenyl groups. Attaching the electron-donor functions to the porphyrazine periphery produces strong perturbations in the electronic and redox properties of the dyes. Their HOMO and LUMO energies, estimated from the optical and redox data, as well as with DFT calculations, raise upon functionalization with amines, while the corresponding frontier orbital energetic levels lower upon functionalization with thioethers, p-methoxyphenyl or p-tert-butylphenyl groups. The effective interaction of peripheral substitution with the macrocycle produces chromophores with panchromatic absorption between 300 and 750-850 nm.
An unsymmetrical, push–pull porphyrazine derivative bearing an isoindole‐4‐carboxylic acid moiety (TT112) is synthesized and incorporated in a dye‐sensitized solar cell (DSSC). The device, which constitutes the first example of a porphyrazine‐sensitized solar cell, exhibits a maximum power conversion efficiency of 3.4 %.
A zinc phthalocyanine endowed with four [18]-crown-6 moieties, ZnPcTeCr, has been prepared and self-assembled with either pyridyl-functionalized perylenebisimides (PDI-Py) or fullerenes (C60-Py) to afford a set of novel electron donor-acceptor hybrids. In the case of ZnPcTeCr, aggregation has been circumvented by the addition of potassium or rubidium ions to lead to the formation of monomers and cofacial dimers, respectively. From fluorescence titration experiments, which gave rise to mutual interactions between the electron donors and the acceptors in the excited state, the association constants of the respective ZnPcTeCr monomers and/or dimers with the corresponding electron acceptors were derived. Complementary transient-absorption experiments not only corroborated photoinduced electron transfer from ZnPcTeCr to either PDI-Py or C60-Py within the electron donor-acceptor hybrids, but also the unexpected photoinduced electron transfer within ZnPcTeCr dimers. In the electron donor-acceptor hybrids, the charge-separated-state lifetimes were elucidated to be close to 337 ps and 3.4 ns for the two PDI-Pys, whereas the longest lifetime for the photoactive system that contains C60-Py was calculated to be approximately 5.1 ns.
Seitenwahl: Die Koordination von Cp*Ru (Cp*=C5Me5) an die konkave und konvexe π‐Oberfläche von Subphthalocyaninen ist ein neuer Ansatz zur Funktionalisierung von Subazaporphyrinen. Die konvexe Seite ist reaktiver, während die Koordination an die konkave Seite den stärkeren diatropen Einfluss auf den Cp*‐Liganden und die größere Veränderung der π‐elektronischen Eigenschaften des Makrocyclus bewirkt.
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