Theoretical Investigation of the Ground and Excited States of Coumarin 151 and Coumarin 120

Cave, Robert J.; Burke, Kieron; Castner, Edward W.

doi:10.1021/jp026071x

Cited by 164 publications

(174 citation statements)

References 119 publications

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“…47,48 TD-DFT has also been shown to be a powerful tool to model the spectroscopic properties of organic fluorophores. 49,50 In addition, empirical HOSE and BLA models, which successfully correlate the structural features of coumarins to their optoelectronic properties, 47,51 are applied in this study as well. 3.1.1.…”

Section: Resultsmentioning

confidence: 99%

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

2013

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Understanding the molecular origins of the optoelectronic properties of fluorophores provides rational guidelines for chemists to synthesize better-performing dyes. Factors affecting the UV−vis absorption spectral shift, molar extinction coefficients, and Stokes shift of fluorophores are herein examined at the molecular level, via both (time-dependent) density functional theory-based calculations and the empirical harmonic-oscillator-stabilization-energy (HOSE) and bond-lengthalternation (BLA) models. The importance of these factors is discussed using six coumarin dyes as exemplars. In particular, a special focus is devoted to the Stokes shift, a critical parameter in fluorophores. It is demonstrated that incorporating a "rotational" substituent in a fluorophore molecule with tailored steric hindrance effects and resonance effects leads to a substantial increase in the Stokes shift, not only in coumarins but also in other chemical dye families: boron-dipyrromethenes (BODIPYs), cyanines, and stilbenes. Structure−property relationships concerning the rotational substituent are discussed in detail with examples of several dye families. These findings lead to the proposal of molecular design criteria that enable one to tune the Stokes shift. Such criteria provide a foundation for the molecular engineering of fluorophores with improved optoelectronic properties.

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Section: Resultsmentioning

confidence: 99%

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

2013

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“…The only way to calculate such corrections for a quantum wire is using TDCDFT, in order to handle currents. In another area, electron and energy transfer in biological molecules, attempts are being made to estimate matrix elements in a TDDFT calculation [36]. Such calculations, using adiabatic local and gradient-corrected approximations, clearly miss any contributions from macroscopic currents.…”

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confidence: 99%

Current-density functional theory of the response of solids

2003

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The response of an extended periodic system to a homogeneous field (of wave-vector q = 0) cannot be obtained from a q = 0 time-dependent density functional theory (TDDFT) calculation, because the Runge-Gross theorem does not apply. Time-dependent current-density functional theory is needed and demonstrates that one key ingredient missing from TDDFT is the macroscopic current. In the low-frequency limit, in certain cases, density polarization functional theory is recovered and a formally exact expression for the polarization functional is given.PACS numbers: 71.15. Mb,78.20.Ci, Density functional theory[1, 2] is a standard approach for calculating ground-state properties of solids [3] and molecules [4]. Time-dependent density functional theory (TDDFT) is an extension of the ground-state formalism based on the Runge-Gross theorem [5]; this establishes a one-to-one correspondence between time-dependent densities and time-dependent one-body potentials. When a time-dependent electric field is applied to a system, this formalism provides a route to its optical response [6]. The response equations of TDDFT have been encoded in standard quantum chemical packages [7], and results for molecules are appearing (see Ref.[8] for many examples). As in the ground-state case, the accuracy depends on the quality of the approximate functional used.There is great interest in applying the same technique to extended systems. While these can be treated well within existing wavefunction technology, using, e.g., the GW approximation and then solving the BetheSalpeter equation for the optical response[9], the allure of a TDDFT approach is its far lower computational cost. Calculations already show that excitonic effects appear to be treatable by going beyond the usual local and semi-local approximations of standard DFT calculations [10,11].There is also a version of the time-dependent theory, called time-dependent current-density functional theory (TDCDFT), that uses the current-density as the basic variable: As the choice of variable (charge density versus current density) appears a matter of convenience, TDCDFT and TDDFT appear to be equivalent (for non-magnetic systems). The time-dependent exchange-correlation potential has been argued to be more amenable to local and semilocal approximation in terms of the current-density [12] and this framework has been used in recent response calculations of solids [13,14] and conjugated polymers [15]. Initial work towards a matrix formulation of the current-density response equations has been presented in Ref. [16].In this paper, we demonstrate a difference in principle between the two approaches when applied to bulk solids. The basic theorems of DFT, ground-state or timedependent, are proven for finite electronic systems (i.e. systems with a boundary). We consider the response of periodic systems (such as the bulk of an insulator or metal) to time-varying electric fields which have a spatially uniform component. We show that TDDFT fails in this case: there is no one-to-one correspondence between ...

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“…7-aminocoumarins are commonly used as laser dyes due to their high quantum yields of emission and low lying ππ* excited states of essentially HOMO to LUMO character. [40][41][42][43][44][45] The first excited singlet states of the 7-aminocoumarins exhibit relatively strong solvatochromic behavior, which has been widely attributed to partial intramolecular charge transfer character (ICT) between the nitrogen atom and carbonyl oxygen atom following extensive studies using TDDFT, [41][42][43][44][45] together with emission and absorption spectroscopy. [46][47][48] Despite this charge separation, unsubstituted 7-aminocoumarins are too small for the partial ICT character to be considered as a long-range charge transfer excited state in TDDFT, and B3LYP therefore performs adequately for calculating excitation energies.…”

Section: Introductionmentioning

confidence: 99%

“…[46][47][48] Despite this charge separation, unsubstituted 7-aminocoumarins are too small for the partial ICT character to be considered as a long-range charge transfer excited state in TDDFT, and B3LYP therefore performs adequately for calculating excitation energies. [41][42][43][44][45] This is important for comparing with TRIR data, as the B3LYP functional is also known to reproduce ground state experimental frequencies well using both scaled harmonic 49,50 and anharmonic 2, 51 techniques, while other commonly used functionals, such as PBE0 52 or CAM-B3LYP 25 and other range corrected functionals often predict frequencies of significantly lower quality. 50,53 Coumarins containing an unsubstituted 7-NH 2 group also show higher fluorescent quantum yields in polar solvents than in non-polar solvents, 54,55 attributed to an increase in positive charge on the N-atom and simultaneous flattening of the 7-NH 2 group in polar solvents, leading to suppression of non-radiative decay from the excited state.…”

Section: Introductionmentioning

confidence: 99%

Calculating singlet excited states: Comparison with fast time-resolved infrared spectroscopy of coumarins

Hanson‐Heine

Wriglesworth

Uroos

et al. 2015

The Journal of Chemical Physics

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In contrast to the ground state, the calculation of the infrared (IR) spectroscopy of molecular singlet excited states represents a substantial challenge. Here we use the structural IR fingerprint of the singlet excited states of a range of coumarin dyes to assess the accuracy of density functional theory based methods for the calculation of excited state IR spectroscopy.It is shown that excited state Kohn-Sham density functional theory provides a high level of accuracy and represents an alternative approach to time-dependent density functional theory for simulating the IR spectroscopy of the singlet excited states.

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Theoretical Investigation of the Ground and Excited States of Coumarin 151 and Coumarin 120

Cited by 164 publications

References 119 publications

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

Current-density functional theory of the response of solids

Calculating singlet excited states: Comparison with fast time-resolved infrared spectroscopy of coumarins

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