Organoimido-Polyoxometalate Nonlinear Optical Chromophores:
A Structural, Spectroscopic, and Computational Study
Version 2 2017-09-14, 04:30
Version 1 2017-08-14, 21:31
Posted on 2017-09-14 - 04:30
Ten
organoimido polyoxometalate (POM)-based chromophores have been
synthesized and studied by hyper-Rayleigh scattering (HRS), Stark
and Resonance Raman spectroscopies, and density functional theory
(DFT) calculations. HRS β0 values for chromophores
with resonance electron donors are significant (up to 139 × 10–30 esu, ∼5 times greater than that of the DAS+ cation), but systems with no donor, or the −NO2 acceptor show no activity, in some cases, despite large DFT-predicted
β-values. In active systems with short (phenyl) π-bridges,
β0 values comfortably exceed that of the purely organic
structural analogue N,N-dimethyl-4-nitroaniline
(DMPNA), and intrinsic β-values, β0/N3/2 (where N is the number of bridge π-electrons)
thus appear to break empirical performance limits (β0/N3/2 vs λmax) for planar organic systems.
However, β0 values obtained for extended systems
with a diphenylacetylene bridge are comparable to or lower than that
of their nitro analogue, N,N-dimethyl-4-[(4-nitrophenyl)ethynyl]-aniline
(DMNPEA). Resonance Raman spectroscopy confirms the involvement of
the POM in the electronic transitions, whether donor groups are present
or not, but Stark spectroscopy indicates that, in their absence, the
transitions have little dipolar character (hence, NLO inactive), consistent
with DFT-calculated frontier orbitals, which extend over both POM
and organic group. Stark and DFT also suggest that β is enhanced
in the short compounds because the extension of charge transfer (CT)
onto the POM increases changes in the excited-state dipole moment.
With extended π-systems, this effect does not increase CT distances,
relative to a −NO2 acceptor, so β0 values do not exceed that of DMNPEA. Overall, our results show that
(i) the organoimido–POM unit is an efficient acceptor for second-order
NLO, but an ineffective donor; (ii) the nature of electronic transitions
in arylimido-POMs is strongly influenced by the substituents of the
aryl group; and (iii) organoimido-POMs outperform organic acceptors
with short π-bridges, but lose their advantage with extended
π-conjugation.
CITE THIS COLLECTION
DataCite
3 Biotech
3D Printing in Medicine
3D Research
3D-Printed Materials and Systems
4OR
AAPG Bulletin
AAPS Open
AAPS PharmSciTech
Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
ABI Technik (German)
Academic Medicine
Academic Pediatrics
Academic Psychiatry
Academic Questions
Academy of Management Discoveries
Academy of Management Journal
Academy of Management Learning and Education
Academy of Management Perspectives
Academy of Management Proceedings
Academy of Management Review
Al-Yasari, Ahmed; Steerteghem, Nick Van; Kearns, Hayleigh; Moll, Hani El; Faulds, Karen; Wright, Joseph A.; et al. (2017). Organoimido-Polyoxometalate Nonlinear Optical Chromophores:
A Structural, Spectroscopic, and Computational Study. ACS Publications. Collection. https://doi.org/10.1021/acs.inorgchem.7b00708
or
Select your citation style and then place your mouse over the citation text to select it.
SHARE
Usage metrics
Read the peer-reviewed publication
AUTHORS (9)
AA
Ahmed Al-Yasari
NS
Nick Van Steerteghem
HK
Hayleigh Kearns
HM
Hani El Moll
KF
Karen Faulds
JW
Joseph A. Wright
BB
Bruce S. Brunschwig
KC
Koen Clays
JF
John Fielden
KEYWORDS
π- bridgesDMPNA2 acceptor showDFT-calculated frontier orbitalsDMNPEANLOHRS β 0 valuesOrganoimido-Polyoxometalate Nonlinear Optical Chromophorestransitionincrease CT distancesResonance Raman spectroscopyStarkβ 0 valuesDFT-predicted β- valuesresonance electron donorsbridge π- electronsResonance Raman spectroscopiesDASPOM increases changes