Second Harmonic Generation and Two-Photon Fluorescence as Nonlinear Optical Properties of Dipolar Mononuclear Sesquifulvalene Complexes

Donor−Acceptor Interaction in Cationic Archetype Mono- and Dinuclear Sesquifulvalene Complexes [(η5-C5H5)Fe{µ-(η5-C5H4)(η7-C7H6)}M′L′]n+ (n = 1, 2)

“…[14] However, 4 was synthesized as a tetrafluoroborate salt and the molecular structure data were obtained with higher accuracy. [4] Solving the molecular structure of complex 6 [MЈLЈ ϭ Ru(η 5 -C 5 Me 5 ) ϩ ] proved to be more difficult because of the presence of three different independent molecules, and the intercalation of four independent solvent molecules of MeNO 2 as evidenced by means of NMR spectroscopy and elemental analysis. The structural data of all three independent molecules of 6 are in agreement within the margin of error.…”

“…However, a draw-back of the HRS method may be fluorescence due to two-photon absorption. [25] A ''low-cost'' check for the two-photon fluorescence was recently described, [4,5] and uses bandpass filters with peak transmittance at different wavelengths introduced in front of the photomultiplier of the HRS set-up. These include long-wavelength measurements, [28,29] time-resolved HRS [28] measurements of the two-photon fluorescence spectrum to abstract the fluorescence contribution to the HRS signal, [30] and a high-frequency demodulating technique to suppress the multiphoton fluorescence contribution to the HRS signal.…”

“…[1,2] As in DϪA substituted polyenes, a description of the bonding situation in mono-and dinuclear sesquifulvalene complexes which demonstrates weak to strong NLO effects, is achieved by different mesomeric forms. [3,4] It would be worthwhile to know, whether a contribution of the cross-conjugated form B to the ground state would affect the SHG according to the BLA in acyclic α,ω-donorϪacceptor substituted conjugated polyenes. [3,4] It would be worthwhile to know, whether a contribution of the cross-conjugated form B to the ground state would affect the SHG according to the BLA in acyclic α,ω-donorϪacceptor substituted conjugated polyenes.…”

Dipolar Second-Order Nonlinear Optical Chromophores Containing Ferrocene, Octamethylferrocene, and Ruthenocene Donors and Strong π-Acceptors: Crystal Structures and Comparison of π-Donor Strengths

“…As discussed in the introduction, there are only a few previously reported crystal structures of metallocenyl dipolar chromophores with very strong non-aromatic organic acceptor groups. Significantly, the current series are the first in which one can directly compare the structures of analogous metallocenyl-polyene-acceptor chromophores with three different metallocenyl donors: ferrocenyl, heavily methylated ferrocenyl, and ruthenocenyl, while previous comparisons between even two types of donors are very limited 12,18,33…”

“…Although 4-nitrophenyl is often regarded as a rather strong π-acceptor, considerably stronger non-aromatic π-acceptors have been developed and incorporated into chromophores to afford much higher molecular nonlinearities; however, few crystal structure determinations have been published for chromophores incorporating these acceptors (Chart 1), i.e., for chromophores in which the zwitterionic resonance structure (Figure 1) might be expected to play a more significant role 9–11. There are also few crystal structures of ruthenocenyl dipolar chromophores12,13 and heavily methylated ferrocenyl14–18 dipolar chromophores; moreover, only in a limited number of these cases are the structures of the analogous unsubstituted ferrocenyl chromophores available for comparison.…”