We report here the design and synthesis of porphyrin-metallocene dyads consisting of a metallocene [either ferrocene or mixed sandwich η(5)-[C5H4(COOH)]Co(η(4)-C4Ph4) connected via an ester linkage at meso phenyl position of either free-base or zinc porphyrin. All these dyad systems were characterized by various spectroscopic and electrochemical methods. A dimeric form of this molecule was observed in the X-ray crystal structure of Zn-TTPCo. The absorption spectra of all four dyads indicated the absence of electronic interactions between porphyrin macrocycle and metallocene in the ground state. However, interestingly, in all four dyads, fluorescence emission of the porphyrin was quenched (19-55%) as compared to their monomeric units. The quenching was more pronounced in ferrocene derivatives rather than cobaltocenyl derivatives. The emission quenching can be attributed to the excited-state intramolecular photoinduced electron transfer from metallocene to singlet excited state of porphyrin and the electron-transfer rates (k(ET)) were established in the range 1.51 × 10(8) to 1.11 × 10(9) s(-1). They were found to be solvent dependent.
Voltage‐stimulated redox‐active materials have received significant attention in the field of organic electronics and sensor technology. Such stimuli‐responsive materials trigger the formation of crystalline nanostructures and facilitate the design of efficient smart devices hitherto unknown. Herein, we report that free‐base and metallo‐tetratolylporphyrin‐linked ferrocene derivatives (H2TTP‐Fc and ZnTTP‐Fc) undergo distinct proton/anion binding mechanism in CHCl3 during bulk electrolysis at applied voltage of 1.4 V to give [H4TTP‐Fc]+Cl− and H+[(Cl)ZnTTP‐Fc]− followed by nanospheres and crystalline 2D nanoflakes formation, confirmed by SEM and TEM images, by methanol vapor diffusion (MVD) approach. Moreover, X‐ray diffraction analysis suggest that protonated H2TTP‐Fc aggregates exhibit amorphous nature, whereas H+[(Cl)ZnTTP‐Fc]− depict crystalline nature from layer‐by‐layer arrangement of nanoflakes assisted by π–π stacking and ion‐dipole interactions.
Charge-transfer (CT) complexes of near-infrared absorbing systems have been unknown until now. Consequently, structural similarities between donor and acceptor are rather important to achieve this phenomenon. Herein, we report electron donors such as non-fused diporphyrin-anthracene (DP), zinc diporphyrin-anthracene (ZnDP) and fused zinc diporphyrin-anthracene (FZnDP) in which FZnDP absorbs in NIR region and permits a CT complex with the electron acceptor, perylene diimide (PDI) in CHCl exclusively. UV/Vis-NIR absorption, H NMR, NOESY and powder X-ray diffraction analysis demonstrated that the CT complex formation occurs by π-π stacking between perylene units in FZnDP and PDI upon mixing together in a 1:1 molar concentration in CHCl , unlike non-fused ZnDP and DP. TEM and AFM images revealed that the CT complex initially forms nanospheres leading to nanorods by diffusion of CH OH vapors into the CHCl solution of FZnDP/PDI (1:1 molar ratio). Therefore, these CT nanorods could lead to significant advances in optical, biological and ferroelectric applications.
We report here the design and synthesis of corrole-metallocene dyads consisting of a metallocene (either ferrocene (Dyad 1) or mixed sandwich [Formula: see text]-[C[Formula: see text]H[Formula: see text](COOH)]Co([Formula: see text]-C[Formula: see text]Ph[Formula: see text] (Dyad 2)) connected via an ester linkage at meso phenyl position. Both the dyads were characterized by [Formula: see text]H NMR, MALDI-TOF, UV-visible, fluorescence spectroscopies (steady-state, picosecond time-resolved), femtosecond transient absorption spectroscopy (fs-TA) and electrochemical methods. The absorption spectra of these dyads showed slight broadening and splitting of the Soret band that indicates a weak ground state interaction between the corrole macrocycle and metallocene part of the present donor–acceptor (D–A) system. However, in both the dyad systems, fluorescence emission of the corrole was quenched in polar solvents as compared to its parent compound 10-(4-hydroxyphenyl)-5,15-bis-(pentafluorophenyl ) corrole (Ph-Corr). The quenching was more pronounced in ferrocene derivatives than in cobaltocenyl derivatives. Transient absorption studies confirm the absence of photoinduced electron transfer from metallocene to correl for these dyad systems and the quenching of singlet state of corrole is found to enhance intersystem crossing due to heavy atom effect.
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