Efficient heterogeneous photosensitizing materials require both large accessible surface areas and excitons of suitable energies and with well‐defined spin structures. Confinement of the tetracationic cyclophane (ExBox4+) within a nonporous anionic polystyrene sulfonate (PSS) matrix leads to a surface area increase of up to 225 m2g−1in ExBox•PSS. Efficient intersystem crossing is achieved by combining the spin‐orbit coupling associated to Br heavy atoms in 1,3,5,8‐tetrabromopyrene (TBP), and the photoinduced electron transfer in a TBP⊂ExBox4+supramolecular dyad. The TBP⊂ExBox4+complex displays a charge transfer band at 450 nm and an exciplex emission at 520 nm, indicating the formation of new mixed‐electronic states. The lowest triplet state (T1, 1.89 eV) is localized on the TBP and is close in energy with the charge separated state (CT, 2.14 eV). The homogeneous and heterogeneous photocatalytic activities of the TBP⊂ExBox4+, for the elimination of a sulfur mustard simulant, has proved to be significantly more efficient than TBP and ExBox+4, confirming the importance of the newly formed excited‐state manifold in TBP⊂ExBox4+for the population of the low‐lying T1state. The high stability, facile preparation, and high performance of the TBP⊂ExBox•PSS nanocomposites augur well for the future development of new supramolecular heterogeneous photosensitizers using host–guest chemistry.
- NSF-PAR ID:
- 10323108
- Date Published:
- Journal Name:
- Physical Chemistry Chemical Physics
- Volume:
- 23
- Issue:
- 41
- ISSN:
- 1463-9076
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract A molecular rotor is created when a 2,1,3‐benzothiadiazole rotator is incorporated into a rigid arylene ethynylene framework supported by pyridine coordination to a metal (Ag+or PdCl2) guest. Comparisons to a similarly sized naphthyl rotator via1H NMR spectroscopy provide insights into the movement of these bicyclic rotators relative to the rigid stator framework. Chemical shift increases of 0.3 ppm, or more, upon metal complexation are consistent with through‐space interaction of the central arene with a bound PdCl2guest. Further study via X‐ray crystallography illustrates that rotation of the 2,1,3‐benzothiadiazole unit in the solid state is likely hampered by relatively strong chalcogen bonding (N⋅⋅⋅S distance of 2.93 Å), forming 2S‐2N squares between benzothiadiazoles of neighboring complexes. Strong π–π interactions (3.29–3.36 Å) between neighboring complexes likewise restrict solid‐state rotation of the potential benzothiadiazole rotator. Modest changes to UV–vis spectra upon metal coordination suggest that electronic properties are mostly independent of stator configuration.
-
more » « less
Abstract We report the synthesis and X‐ray crystal structure of a cucurbituril–triptycene chimeric receptor (
1 ). Host1 binds to guests typical of CB[6]–CB[8], but also binds to larger guests such as blue box (20 ) and the Fujita square (22 ). Intriguingly, the geometries of the1 ⋅20 and1 ⋅22 complexes blur the lines between host and guest in that both components fulfill both roles within each complex. The fluorescence output of1 is fully quenched by the formation of complexes with pyridinium‐derived guests. -
more » « less
Abstract We report the synthesis and X‐ray crystal structure of a cucurbituril–triptycene chimeric receptor (
1 ). Host1 binds to guests typical of CB[6]–CB[8], but also binds to larger guests such as blue box (20 ) and the Fujita square (22 ). Intriguingly, the geometries of the1 ⋅20 and1 ⋅22 complexes blur the lines between host and guest in that both components fulfill both roles within each complex. The fluorescence output of1 is fully quenched by the formation of complexes with pyridinium‐derived guests. -
The effect of acceptor strength on excited state charge‐transfer (CT) and charge separation (CS) in central phenothiazine (PTZ) derived symmetric 1 (PTZ-(TCBD-TPA)2) and asymmetric, 2 (PTZ-(TCBD/DCNQ-TPA)2) push-pull conjugates, in which triphenylamine (TPA) act as end capping and 1,1,4,4–tetracyanobuta–1,3–diene (TCBD) and cyclohexa–2,5–diene–1,4–ylidene–expanded TCBD (DCNQ) act as electron acceptor units is reported. Due to strong push-pull effects, intramolecular charge transfer (ICT) was observed in the ground state extending the absorption into the near-IR region. Electrochemical, spectroelectrochemical and computational studies coupled with energy level calculations predicted both 1 and 2 to be efficient candidates for ultrafast charge transfer. Subsequent femtosecond transient absorption studies along with global target analysis, performed in both polar and nonpolar solvents, confirmed such processes in which the CS was efficient in asymmetric 2 having both TCBD and DCNQ acceptors in polar benzonitrile while in toluene, only charge transfer was witnessed. This work highlights significance of number and strength of electron acceptor entities and the role of solvent polarity in multi-modular push-push systems to achieve ultrafast CS.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D1CP03000K
