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Curved ?-conjugated corannulene dimer diradicaloids.

ABSTRACT: So far, most reported open-shell singlet diradicaloids are based on planar ?-conjugated molecules. Herein, we report the bridged corannulene dimer diradicaloids, Cor-D1 and Cor-D2, both showing a three-dimensional curved ?-conjugated structure. Cor-D1 has a small diradical character (y0 = 5.4%) and behaves more like a closed-shell quinoidal compound at room temperature, while Cor-D2 is a typical open-shell diradicaloid with a larger diradical character (y0 = 16.9%). Both compounds exhibited paramagnetic activity at elevated temperatures, with a singlet-triplet energy gap (?ES-T) of -8.4 and -3.0 kcal mol-1, respectively. X-ray crystallographic analysis revealed that both molecules have a dumbbell-shaped geometry, with the two terminal corannulene bowls bent to opposite directions. The spin is largely delocalized onto the two bowls in Cor-D2 and there are multiple [CH···?] interactions between the neighboring bowls. Chemical oxidation/reduction to their respective dications/dianions results in global aromaticity with [4n + 2] ?-electrons delocalized through the periphery of the whole framework.

SUBMITTER: Wang Q

PROVIDER: S-EPMC5994875 | biostudies-other | 2018 Jun

REPOSITORIES: biostudies-other

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Curved π-conjugated corannulene dimer diradicaloids.

Wang Qing Q Hu Pan P Tanaka Takayuki T Gopalakrishna Tullimilli Y TY Herng Tun Seng TS Phan Hoa H Zeng Wangdong W Ding Jun J Osuka Atsuhiro A Chi Chunyan C Siegel Jay J Wu Jishan J

Chemical science 20180516 22

So far, most reported open-shell singlet diradicaloids are based on planar π-conjugated molecules. Herein, we report the bridged corannulene dimer diradicaloids, Cor-D1 and Cor-D2, both showing a three-dimensional curved π-conjugated structure. Cor-D1 has a small diradical character (y0 = 5.4%) and behaves more like a closed-shell quinoidal compound at room temperature, while Cor-D2 is a typical open-shell diradicaloid with a larger diradical charact ...[more]

PMID: 29938041

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Project description:BackgroundMovement regularities are inherently present in automated goal-directed motions of the primate's arm system. They can provide important signatures of intentional behaviours driven by sensory-motor strategies, but it remains unknown if during motor learning new regularities can be uncovered despite high variability in the temporal dynamics of the hand motions.MethodsWe investigated the conservation and violation of new movement regularity obtained from the hand motions traced by two untrained monkeys as they learned to reach outwardly towards spatial targets while avoiding obstacles in the dark. The regularity pertains to the transformation from postural to hand paths that aim at visual goals.ResultsIn length-minimizing curves the area enclosed between the Euclidean straight line and the curve up to its point of maximum curvature is 1/2 of the total area. Similar trend is found if one examines the perimeter. This new movement regularity remained robust to striking changes in arm dynamics that gave rise to changes in the speed of the reach, to changes in the hand path curvature, and to changes in the arm's postural paths. The area and perimeter ratios characterizing the regularity co-varied across repeats of randomly presented targets whenever the transformation from posture to hand paths was compliant with the intended goals. To interpret this conservation and the cases in which the regularity was violated and recovered, we provide a geometric model that characterizes arm-to-hand and hand-to-arm motion paths as length minimizing curves (geodesics) in a non-Euclidean space. Whenever the transformation from one space to the other is distance-metric preserving (isometric) the two symmetric ratios co-vary. Otherwise, the symmetric ratios and their co-variation are violated. As predicted by the model we found empirical evidence for the violation of this movement regularity whenever the intended goals mismatched the actions. This was manifested in unintended curved "after-effect" trajectories executed in the absence of obstacles. In this case, the system was "perturbed" away from the symmetry but after several repeats it recovered its default state.ConclusionsWe propose this movement regularity as a sensory-motor transformation invariant of intentional acts.

Dataset Information

Curved ?-conjugated corannulene dimer diradicaloids.

Publications

Curved π-conjugated corannulene dimer diradicaloids.

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