The unprecedented dependence of final charge separation efficiency as af unction of donor-acceptor interaction in covalently-linked molecules with ar ectilinear rigid oligo-p-xylene bridge has been observed. Optimization of the donor-acceptor electronic coupling remarkably inhibits the undesirable rapid decayofthe singlet charge-separated state to the ground state,y ielding the final long-lived, triplet chargeseparated state with circa 100 %e fficiency.T his finding is extremely useful for the rational design of artificial photosynthesis and organic photovoltaic cells towarde fficient solar energy conversion.
The combination of porphyrin as a sensitizer and a ruthenium complex as a water oxidation catalyst (WOC) is promising to exploit highly efficient molecular artificial photosynthetic systems.
Highly syndiotactic poly(methy1 methacry1ate)s (PMMAs) with narrow molecular weight distribution (MWD) were prepared by polymerization of MMA in toluene at low temperatures, initiated with tert-butyllithium (t-C,H,Li) combined with trialkylaluminium compounds such as triethyl-, tributyl, and trioctylaluminium (mole ratio AI/Li 2 3). Polymerization was initiated by the t-C,H, anion and proceeded in a living manner. Several alkyl methacrylates were also polymerized with t-C,H&i-(n-C,H,),AI to give highly syndiotactic polymethacrylates with narrow MWD. Highly syndiotactic block and random copolymers of MMA and ethyl methacrylate were obtained by this initiator.
Nano-confined spaces in nanoporous materials enable anomalous physicochemical phenomena. While most nanoporous materials including metal-organic frameworks are mechanically hard, graphene-based nanoporous materials possess significant elasticity and behave as nanosponges that enable the force-driven liquid–gas phase transition of guest molecules. In this work, we demonstrate force-driven liquid–gas phase transition mediated by nanosponges, which may be suitable in high-efficiency heat management. Compression and free-expansion of the nanosponge afford cooling upon evaporation and heating upon condensation, respectively, which are opposite to the force-driven solid–solid phase transition in shape-memory metals. The present mechanism can be applied to green refrigerants such as H
2
O and alcohols, and the available latent heat is at least as high as 192 kJ kg
−1
. Cooling systems using such nanosponges can potentially achieve high coefficients of performance by decreasing the Young’s modulus of the nanosponge.
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