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CATEGORIES:Theory - Chemistry Research Interest Group
SUMMARY:Highly Polar Supramolecular Species with Enhanced 
 IR Activity - Professor Fedor Naumkin\, University
  of Ontario
DTSTART;TZID=Europe/London:20190515T141500
DTEND;TZID=Europe/London:20190515T151500
UID:TALK115180AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/115180
DESCRIPTION:Highly polar molecular systems are in need for man
 y important practical applications based on light-
 matter interactions\, e.g. solar energy utilizatio
 n.\n   Novel insertion complexes of polar molecule
 s non-covalently trapped between alkali-halide (MX
 ) counter-ions are compared to non-polar-based cou
 nterparts [1-3]. The M-molecule-X systems can exhi
 bit from a metastability to a stability by up to 1
  eV relative to molecule + MX. The polar-molecule 
 insertion complexes can be even more strongly boun
 d than the common dipole-dipole MX-molecule confor
 mers and separated from those by significant energ
 y barriers\, thus being thermodynamically stable s
 pecies with very large dipoles of up to > 25 D.\n 
   Interesting features include the nonobvious cont
 ributions of the molecule polarity to the system s
 tability and dipole moment\, the cooperative non-a
 dditivity of pair interactions\, molecule reshapin
 g and linking by framing ion-pairs. The latter is 
 demonstrated by a (M-molecule-X)2 dimer\, stable t
 o dissociation and extremely polar at about 50 D.\
 n   For the corresponding (M-molecule-X)– anions\,
  relative stabilities of various conformers and ba
 rriers between them vary significantly relative to
  the neutral counterparts. Feasible pathways for e
 xperimental production of the M-molecule-X species
  are analyzed using the energy profiles for the ne
 utral and anionic systems.\n   Due to neutralizati
 on of the M-X charge-transfer in the excited tripl
 et state\, these complexes represent unique spin-c
 ontrolled dipole-switch molecular systems with a l
 arge dipole reversibly turned off or even inverted
  by the spin state\, potentially allowing various 
 spin/optoelectronic applications. The IR spectra a
 re predicted to considerably vary and sensitively 
 indicate the formation of both the M-molecule-X an
 d MX-molecule conformers\, with intensities up to 
 an order of magnitude higher in the complexes\, fa
 cilitating their reliable detection and differenti
 ation in experiments. The above indicates possible
  ways of adding polarity (via attached ion-pairs) 
 to nonpolar molecules and thus of their efficient 
 experimental detection and characterization. The s
 o increased attraction could promote molecular sel
 f-assembly and chemical reactions as well. While m
 etastable systems suggest possible applications fo
 r high-capacity energy storage. \n\n[1]   F. Y. Na
 umkin\, J. Phys. Chem. A 121\, 4545 (2017). \n[2] 
   S. Kerr\, F. Y. Naumkin\, New J. Chem.\, 41\, 13
 576 (2017).\n[3]   B. Cochrane\, F. Y. Naumkin\, C
 hem. Phys. Lett. 643\, 137 (2016).\n
LOCATION:Department of Chemistry\, Cambridge\, Unilever lec
 ture theatre
CONTACT:Lisa Masters
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