Synthesis of Chiral Donor–Acceptor Dyes to Study Electron Transfer Across a Chiral Bridge

Abstract

Chiral organic dyes comprising a donor (D), spacer (S), primary acceptor (A1), chiral bridge (B(S)), and final acceptor/radical (A2)/(R) have been synthesized and fully characterized. The goal behind this synthetic pursuit is to study whether the chiral dyes can impart a chiral-induced spin selectivity (CISS) spin-filtering effect during an intramolecular charge-transfer (CT) process. Additionally, appending a stable free radical (SFR) allows the study of how an unpaired spin influences the CT state. The dyes are reported to vary in the position of (A1) with respect to (B(S)). Two series of dyes have been synthesized: one series incorporates (A1) before (B(S)) and the second series places (A1) after (B(S)). In the case where (A1) is before (B(S)), CT is observed between (D) and (A1), but the CT state does not transverse over the chiral bridge to the final (A2)/(R) termini. However, when (A1) is placed after (B(S)), CT over or through the bridge occurs. Computations support the experimental data, which indicate that it is necessary to have (A1) located after (B(S)) to achieve CT over the chiral bridge. Hence, the second set of dyes are optimal candidates to explore intramolecular CISS.

Diamond surface engineering for molecular sensing with nitrogen—vacancy centers

“…In future experiments, chiral molecules could be instead assembled directly on diamond surfaces, in close proximity to NV centers, with externally driven charge transfer to generate spin polarization. 393,[415][416][417][418] Adsorbed molecules supporting charge-and spin-polarized electrons would induce both electric and magnetic fields at the NV position, enabling new methods for characterization of CISS that could provide novel mechanistic insight.…”

Origin of Chirality Induced Spin Selectivity in Photoinduced Electron Transfer

“…3,4,26,31,41 In fact, the first examples of such molecules have already been synthesized. 42 These systems could find an array of uses in single-molecule-scale quantum computing and quantum information applications. 1,40 It is also known that electron hopping occurs in many important biological electron transfer systems, 22 such as in photosynthesis in photosystem I 20 and in cryptochromes, which are involved in signaling and potentially in magnetoreception.…”

“…This theory of the CISS effect in molecular systems opens the door to many potential avenues of research. With a theory for the ZQCs and spin-polarizations generated in chiral molecules, well-established principles for synthetically tuning electronic properties of donor–acceptor systems , could be applied to engineer systems displaying large CISS effects, which can be probed using a variety of possible experiments. ,,,, In fact, the first examples of such molecules have already been synthesized . These systems could find an array of uses in single-molecule-scale quantum computing and quantum information applications. , It is also known that electron hopping occurs in many important biological electron transfer systems, such as in photosynthesis in photosystem I and in cryptochromes, which are involved in signaling and potentially in magnetoreception .…”

Photoinduced Cascading Charge Transfer in Perylene Bisimide-Based Triads

“…Inspired by natural photosynthetic systems, artificial multichromophoric systems have been developed for highly efficient solar conversion. , Commonly, the scheme of organizing multiple chromophores is expected for the sufficient solar harvesting and the long-lived charge transfer (CT)/charge separation state through multistep CT processes. − Multitudinous designs of bichromophoric architectures that incorporate electron donors (D) and electron acceptors (A) for the stable CT state have been demonstrated, − and great efforts have been devoted to the selection and permutation of plentiful D and A building blocks on an organic molecular level. − In the past years, multichromophoric architectures with more than one D or A units such as D–A–D, − A–D–A, ,− D–A 1 –A 1 , − and D–A 1 –A 2 ,− structures have been developed relative to the classic bichromophoric D–A architectures. Among multitudinous multichromophoric architectures, the D–A 1 –A 2 architecture is a feasible and facile strategy to increase the lifetime of CT states, which stem from the appropriate CT rate of two concatenate building units for further charge transfer to the third unit before charge recombination (CR) .…”