Four new subphthalocyanine-based capsules have been synthesized and characterized. These supramolecular systems have been successfully employed for the encapsulation of fullerenes and probed by a wide range of characterization methods, including NMR, UV-vis and fluorescence spectroscopy, electrospray ionization mass spectrometry, and electrochemistry. Furthermore, the binding constants of the host guest complexes were estimated. Finally, the photophysical properties revealed that the subphthalocyanines undergo a transduction of singlet excited-state energy to the fullerene inside the cavity upon photoexcitation.

Herein, we investigate the association of a fullerene fragment, hemifullerene C30H12, with an electron-donating bowl-shaped tetrathiafulvalene derivative (truxTTF). UV/Vis titrations and DFT calculations support formation of the supramolecular complex, for which an association constant of log Ka = 3.6±0.3 in CHCl3 at room temperature is calculated. Remarkably, electron transfer from truxTTF to C30H12 to form the fully charge-separated species takes place upon irradiation of the associate with light, constituting the first example in which a fullerene fragment mimics the electron-accepting behavior of fullerenes within a supramolecular complex.

Preparation of exTTF-(crown ether)2 receptors, which host C60, to understand the nature of the fullerene–crown ether interaction. A combination of experimental and in silico studies suggest that it results from the interplay of donor–acceptor, ð–ð , n–ð and CH•••ð interactions.

Inorganic meets organic: Covalent bonds (peptide condensation) and noncovalent interactions (π–π stacking) have been employed en route toward versatile donor–acceptor inorganic–organic nanohybrids, QD‐pyrene/SWNT. A charge‐transfer event within the hybrid transforms the excitonic state of the quantum dot into a charge‐transfer state that has a lifetime of several nanoseconds.

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.

We report that supramolecular polymer films composed of a 2:1 mixture of monodiamidopyridine diketopyrrolopyrrole (DPP) electron donors and perylene bisdiimide (PDI) electron acceptors undergo photoinduced charge transfer in the solid state. Film formation is guided by complementary noncovalent interactions programmed into the molecular components, resulting in a film architecture comprised of polymer wires with order across the molecular-to-macroscopic continuum. Using ultrafast transient absorption spectroscopy, we show that recombination lifetimes increase 1000-fold compared to the same supramolecular polymers in solution. Supramolecular donor−acceptor polymer films, such as these, that are designed by considering structure and electron transfer dynamics synergistically could lead to breakthroughs in organic optoelectronics. ■ INTRODUCTIONSignificant efforts have been devoted toward improving the performance of small molecule organic photovoltaics (OPVs); 1−4 however, challenges still remain with regard to understanding, controlling, and ultimately optimizing the photon-to-current conversion within the photoactive layer. Natural photosynthetic processes that efficiently convert sunlight to fuel rely upon precisely positioned assemblies of photofunctional chromophores for light harvesting, charge separation, and catalysis. 5 Light conversion in the reaction center involves the synergistic combination of superstructure and ultrafast electron transfer to form long-lived radical pairs. 6,7 The near unity conversion of light to chemical energy in the reaction center is a compelling model for future solar technologies 8 and has inspired the design of organic materials for artificial photosynthesis. 9−11 Similar to the reaction center, the photoactive layers of OPVs require appropriately matched donor and acceptor frontier molecular orbital levels and electronic coupling that enable rapid charge generation, and the resulting films must also possess multilength scale order for charge migration through the films. 12,13 Approaches for designing these materials must consider ease of preparation, solar spectrum absorption, electron transfer dynamics, and film order together to achieve efficient charge generation. Supramolecular polymers are a promising class of materials that could potentially be used for preparing organized films that undergo photoinduced charge separation. Supramolecular polymers are macromolecules whose monomeric repeat units are held together by noncovalent bonds, and their noteworthy characteristics include assembly from easy-to-prepare small molecules, hierarchical structure, and stimuli responsiveness. 14−19 Several supramolecular polymer systems have been explored in the context of photoinduced charge separation in solution 20−23 and the solid-state, 24−27 including a system we developed composed of a monodiamidopyridine diketopyrrolopyrrole (mDPP) electron donor and a perylene bisimide (PDI) electron acceptor 28 that assembles into 2:1 mDPP:PDI helical supramolecular polymers ( Figure 1a) as a re...

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.

Herein, we report the synthesis of guanidinium bis-porphyrin tweezers 1 and fullerene carboxylate 3, their assembly into a novel supramolecular 1@3 electron donor-acceptor hybrid, and its characterization. In solution, the binding constant affording 1@3 is exceptionally high. 1@3, which features a highly confined topography, builds up from a combination of guanidinium-carboxylate hydrogen bonding and π-π stacking/charge-transfer motifs. The latter is governed by interactions between the electron-donating porphyrin and the electron-accepting fullerene. Importantly, positive cooperativity between the applied binding motifs is corroborated by a number of experimental techniques, such as NMR, absorption, fluorescence, etc. In addition, transient absorption experiments shed light onto electron-transfer processes taking place in the ground state and upon photoexcitation. In fact, porphyrin excitation powers an electron transfer to the fullerene yielding charge separated state lifetimes in the nanosecond regime.