Molecular engineering of push–pull dipolar and quadrupolar molecules for two-photon absorption: A multivalence-bond states approach

Barzoukas, M.; Blanchard‐Desce, Mireille

doi:10.1063/1.1288367

Cited by 175 publications

(179 citation statements)

References 41 publications

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“…These states dominate the low-energy physics of the chromophores and suggest the use of a three-state picture to describe their electronic structure: indeed a three-state model has already been successfully adopted to describe quadrupolar donor-acceptor based compounds for NLO applications and to optimize their two-photon absorption cross-section. 50,51 However, the solvatochromism of quadrupolar dyes was not addressed in these papers. Here, for the first time, we extend the three-state electronic model to account at the same time for electron-vibration coupling and for solvation effects.…”

Section: Bistability and Symmetry Breaking: Model And Conceptsmentioning

confidence: 99%

Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism

et al. 2006

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We present a joint theoretical and experimental work aimed to understand the spectroscopic behavior of multipolar dyes of interest for nonlinear optics (NLO) applications. In particular, we focus on the occurrence of broken-symmetry states in quadrupolar organic dyes and their spectroscopic consequences. To gain a unified description, we have developed a model based on a few-state description of the charge-transfer processes characterizing the low-energy physics of these systems. The model takes into account the coupling between electrons and slow degrees of freedom, namely, molecular vibrations and polar solvation coordinates. We predict the occurrence of symmetry breaking in either the ground or first excited state. In this respect, quadrupolar chromophores are classified in three different classes, with distinctively different spectroscopic behavior. Cases of true and false symmetry breaking are discriminated and discussed by making resort to nonadiabatic calculations. The theoretical model is applied to three representative quadrupolar chromophores: their qualitatively different solvatochromic properties are connected to the presence or absence of broken-symmetry states and related to two-photon absorption (TPA) cross-sections. The proposed approach provides useful guidelines for the synthesis of dyes for TPA application and represents a general and unifying reference frame to understand energy-transfer processes in multipolar molecular systems, offering important clues to understand basic properties of materials of interest for NLO and energy-harvesting applications.

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Section: Bistability and Symmetry Breaking: Model And Conceptsmentioning

confidence: 99%

Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism

et al. 2006

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“…For this class of chromophores, a three-state model can be adopted, which is based on the neutral and two zwitterionic (degenerate) states. [154,155] The inversion symmetry imposes that the lower energy excited state (e) is one-photon allowed, whereas the higher-energy one (e ) is accessible through two-photon absorption. Again, the diagonal γ zzzz component along the principal molecular axis provides the major contribution to the two-photon process.…”

Section: Effective 2/3-state Modelsmentioning

confidence: 99%

“…[155] This corresponds to a ground state described by an equal mixing of the neutral and the symmetric zwitterionic resonance forms. If this is the case, both numerator and denominator in Eq.…”

Section: Effective 2/3-state Modelsmentioning

confidence: 99%

“…The reliability of a three-state model for quadrupolar chromophores with enhanced TPA response has been widely tested and accepted (e.g., [90,157,158] ). Similar to the two-state case, MIX [155] or ρ [158] parameter can be chosen to describe molecular properties in the framework of the three-state model.…”

Section: Effective 2/3-state Modelsmentioning

confidence: 99%

“…[146][147][148][149] Since only a few electronic transitions often predominate in the nonlinear resonant spectra of organic molecules, effective few-state models have become very popular for rational molecular design of NLO-phores. [90,103,127,[150][151][152][153][154][155][156][157][158][159][160] For branched structures, the Frenkel exciton model has been shown to provide a valuable qualitative tool to connect the photophysical properties of branched chromophores to those of their corresponding monomeric counterpart. [113,120,[161][162][163] Theoretical limits for TPA activities have also been explored as well.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Two‐Photon Absorption of Organic Chromophores: Theoretical and Experimental Assessments

et al. 2008

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Nanoscale Push-Push Dihydrophenanthrene Derivatives as Novel Fluorophores for Two-Photon-Excited Fluorescence

et al. 2001

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Molecular two-photon absorption (TPA) [1] has gained interest over recent years owing to its applications in various fields, including spectroscopy, optical data storage, [2] optical power limitation, [3] and microfabrication. [4] Among these, two-photon-excited fluorescence (TPEF) has gained widespread popularity in the biological community and has given rise to the technique of two-photon laser scanning fluorescence microscopy. [5] In standard fluorescence microscopy, molecular excitation is caused by the absorption of a single photon. Molecular excitation by the simultaneous absorption of two photons, however, presents several advantages including a capacity for a highly confined excitation and intrinsic three-dimensional resolution, and the possibility of imaging at an increased penetration depth in tissue, with reduced photodamage and background fluorescence. [5b] TPEF microscopy was initially developed by using conventional fluorophores whose TPA characteristics were not optimized and thus led to the necessity of high laser intensities and/or fluorophore concentrations. It has become clear that the development of TPEF microscopy would greatly benefit from the design of novel fluorophores specifically engineered for efficient TPEF. Key features for such a purpose are large TPA cross sections s 2 and a high fluorescence quantum yield F. We present herein the design, synthesis, and potential applications for membrane imaging of a series of novel fluorophores that demonstrate enhanced TPEF cross sections in the visible-red or near-IR region.It has been observed recently that symmetrical conjugated molecules that bear two electron-donating D (or electronwithdrawing A) end groups can display high nonlinear absorption characteristics [3] and large s 2 values. [6] Such behavior is correlated to an intramolecular charge redistribution that occurs between the ends and the center of the molecule. Enhancing this quadrupolar charge transfer, either in D-AA-D or A-DD-A derivatives, [7] or by lengthening the conjugated system, [6b,c] can lead to significant increases in s 2 . Unfortunately, this often leads to a decrease in the fluorescence quantum yield. Based on these observations, our aim has been to design elongated systems that display large s 2 in the visible-red/NIR region (700 ± 900 nm), while maintaining high fluorescence quantum yields. Our molecular-engineering strategy is based on the push ± push (e.g. bis-donor) functionalization of a semirigid nanoscale conjugated system. The structure is built from the symmetrical grafting of two elongated rods that bear a donating end group on a rigid conjugated core (Figure 1). ArAr NR 1 R 2 D D R 2 R 1 N n n rigid core conjugated rod conjugated rod Figure 1. Molecular engineering of push ± push fluorophores with high two-photon absorptivity. Based on earlier work, [6a] the dihydrophenanthrene moiety was chosen as the central building block. The extending rods were built from arylene ± vinylene oligomers which were expected to ensure electronic conjugation and maint...

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Molecular engineering of push–pull dipolar and quadrupolar molecules for two-photon absorption: A multivalence-bond states approach

Cited by 175 publications

References 41 publications

Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism

Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism

Enhanced Two‐Photon Absorption of Organic Chromophores: Theoretical and Experimental Assessments

Nanoscale Push-Push Dihydrophenanthrene Derivatives as Novel Fluorophores for Two-Photon-Excited Fluorescence

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