Isomer-selective dative bond O -> M (M = Si, Ge) for designing new photochromic hemi-indigo systems
Résumé
New photochromic systems MY2X-HI (M = Si, Ge) were designed (at the DFT level of theory) by replacing the hydrogen atom in the nitrogen of the pyrrole ring of hemi-indigo, HI, with silyl- or germyl-substituents. The E isomers of MY2X-HI contain a dative bond O -> M (pentacoordinated atom M) both in the ground S-0 and in the excited S-1 states. This leads to a significant difference in the absorption and fluorescence maxima (lambda(fl) - lambda(abs)) of the Z and E forms of hypervalent hemi-indigos; this difference is more than twice that of the parent HI. There is a trend to increasing separation of first pi ->pi* absorption bands of the E and Z isomers of MY2X-HI with the increase in their relative stability.
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Doronina et al-2021-Isomer-selective dative bond O→M (M = Si, Ge) for designing new photochromic.pdf (1.38 Mo)
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Doro_1-s2.0-S0022328X21005106-mmc1.pdf (419.88 Ko)
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