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Four relatively rigid assemblies I–IV have been designed to understand the factor governing the photoinduced electron transfer (PET) process in 2-ureido-4[1 H ]-pyrimidinone quadruple hydrogen-bonded systems. Upon excitation, PET from the N,N -dimethylaniline group to the singlet anthracene takes place giving rise to a long-lived charge-separation state up to 56 μs for assembly I and 13 μs for assembly II . Moreover, the introduction of CH 2 group(s) to assemblies I and II can significantly influence, or even switch off the intra-assembly PET process. Spectroscopic and electrochemical studies demonstrate efficient electronic communication responsible for the PET process in 2-ureido-4[1 H ]-pyrimidinone quadruple hydrogen-bonded N , N -dimethylaniline-anthracene assemblies. The fast single-step electron-transfer and slow charge-recombination, as well as the high excitation energy conversion efficiency (78%), enable the assemblies to be advantageous for high light-energy conversion.

2-Ureido-4(1H)-pyrimidinone-bridged ferrocene-fullerene assembly I is designed and synthesized for elaborating the photoinduced electron-transfer processes in self-complementary quadruply hydrogen-bonded modules. Unexpectedly, steady-state and time-resolved spectroscopy reveal an inefficient electron-transfer process from the ferrocene to the singlet or triplet excited state of the fullerene, although the electron-transfer reactions are thermodynamically feasible. Instead, an effective intra-assembly triplet-triplet energy-transfer process is found to be operative in assembly I with a rate constant of 9.2×10(5) s(-1) and an efficiency of 73% in CH(2)Cl(2) at room temperature.

2-Ureido-4[1H]-pyrimidinone quadruple hydrogen-bonded assembly 1·1 containing N,N-dimethylaminophenyl moiety exhibits a sensitive response to fluoride anion and lead cation. Spectroscopic studies reveal that the presence of small amount of fluoride anions and lead cations can easily disassemble and intercalate 2-ureido-4[1H]-pyrimidinone hydrogen-bonded supramolecular architectures.

2-Ureido-4[1H]-pyrimidinone-bridged porphyrin–fullerene dyad assemblies I–II were designed and synthesized to investigate the intra-assembly photoinduced electron transfer (PET) via the quadruple complementary hydrogen bonds. Steady-state and time-resolved spectroscopy demonstrate that upon excitation of the porphyrin, electron transfer to the fullerene occurs with rate constants (quantum efficiency) of 1.6 × 108 s–1 (60%) and 4.2 × 108 s–1 (44%) for assembly I and II, respectively, in a CH2Cl2 solution at room temperature. More importantly, the rate of charge recombination was found to be rather slow with a lifetime of charge separation (CS) up to 9.8 μs for assembly I and 4.0 μs for assembly II. Because the relatively rigid assemblies prevent the porphyrin and fullerene from any intra-assembly collisions either through solvent or through space mechanisms, the quadruple complementary hydrogen bonds play crucial roles in mediating the intra-assembly PET process. This is, to the best of our knowledge, the ...