Intermolecular states in organic dye dispersions: excimers vs. aggregates

Musser, Andrew J.; Rajendran, Sai Kiran; Georgiou, Kyriacos; Gai, Lizhi; Grant, Richard T.; Shen, Zhen; Cavazzini, Marco; Ruseckas, Arvydas; Turnbull, Graham A.; Samuel, Ifor D. W.; Clark, Jenny

doi:10.1039/c7tc02655b

Cited by 74 publications

(88 citation statements)

References 41 publications

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“…Other authors have also observed that BODIPY dyes of LBDP1 type can show excimer fluorescence at high local concentrations when performing studies in membranes. [57][58][59] Chujo et al studied the aggregation behaviour of a series of amphiphilic LBDP3 dyes (with different PEG substituents) in mixtures of THF:water. [20] One of these BODIPYs showed aggregates derived from H dimers, forming spherical nanoparticles in aqueous THF (with a diameter of 3.9 � 0.6 nm, assembling into larger aggregates of ca.…”

Section: Previous Observations On Associationmentioning

confidence: 99%

On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated Boron‐Dipyrromethene (BODIPY) Dyes in Aqueous Solution

et al. 2019

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The tendency of boron‐dipyrromethene (BODIPY) dyes to associate in water is well known, and usually a cause for inferior fluorescence properties. Synthetic efforts to chemically improve BODIPYs’ water solubility and minimize this problem have been numerous in the past. However, a deeper understanding of the phenomena responsible for fluorescence quenching is still required. Commonly, the spectroscopic behaviour in aqueous media has been attributed to aggregate or excimer formation, with such works often centring on a single BODIPY family. Herein, we provide an integrating discussion including very diverse types of BODIPY dyes. Our studies revealed that even subtle structural changes can distinctly affect the association behaviour of the fluorophores in water, involving different photophysical processes. The palette of behaviour found ranges from unperturbed emission, to the formation of H or J aggregates and excimers, to the involvement of tightly bound, pre‐formed excimers. These results are a first step to a more generalized understanding of spectroscopic properties vs. structure, facilitating future molecular design of BODIPYs, especially as probes for biological applications.

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Section: Previous Observations On Associationmentioning

confidence: 99%

On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated Boron‐Dipyrromethene (BODIPY) Dyes in Aqueous Solution

et al. 2019

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“…However, we cannot exclude the presence of excimers as a result of  stacking in the excited state (in closely packed aggregates subtle changes in the geometrical arrangement can lead to differential excimer-formation capability), 12,24 since it also provides red-shifted emission patterns, albeit usually with lower fluorescence-deactivation probability than that provided by J-like aggregation. 23 To Figure 3a and corresponding spectra in Figure 3b). Thus, at the fiber ends (see Figure 3a) the fluorescence profile is dominated by the characteristic short-wavelength emission from individual 1 molecules (longer lifetimes), whereas the characteristic red-shifted emission from 1 aggregates prevails at the center of the particle (faster lifetimes).…”

Section: Resultsmentioning

confidence: 99%

Chiral Microneedles from an Achiral Bis(boron dipyrromethene): Spontaneous Mirror Symmetry Breaking Leading to a Promising Photoluminescent Organic Material

et al. 2019

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Supramolecular self-assembly of a highly flexible and achiral meso bis(BODIPY) dye straightforwardly yields fluorescent microfibers exhibiting an intriguing anisotropic photonic behavior. This performance includes the generation of chiroptical activity by means of spontaneous mirror symmetry breaking (SMSB). Repetition of a number of self-assembly experiments demonstrates that the involved SMSB is not stochastic but quasi deterministic in the direction of the induced chiral asymmetry. The origin of these intriguing (chiro)photonic properties is revealed by fluorescent microspectroscopy studies of individual micrometric objects, combined with X-ray diffraction elucidation of microcrystals. Such a study demonstrates that J-like excitonic coupling between bis(BODIPY) units plays a fundamental role in their supramolecular organization, leading to axial chirality. Interestingly, the photonic behavior of the obtained fibers is ruled by inherent non-radiative pathways from the involved push-pull chromophores, and mainly by the complex excitonic interactions induced by their anisotropic supramolecular organization.

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“…Upon the excitation at the vibrational absorption peaks, mirror-imaged fluorescent emission spectra are observed in both molecules, peaking at 686 and 706 nm in the deep red region, respectively, with Stokes-shifts of 216 and 245 cm À1 . [28] Their absorption and emission properties are further investigated in solid state. Although the photoluminescent quantum yields (PLQYs) of red emitters usually suffer from the non-radiative deactivation due to the energetically close lying emissive state and high vibronic state of the ground state, BF-BDP and NF-BDP present decent PLQYs of 0.39 and 0.45, respectively, when taking ZnPc (zinc phthalocyanine) as the reference ( Figure S2).…”

Section: Highly Efficient Deep-red-to Near-infrared-absorbing and Emimentioning

confidence: 99%

Highly Efficient Deep‐Red‐ to Near‐Infrared‐Absorbing and Emissive Benzo/Naphtho[b]furan‐Fused Boron Dipyrromethene (BODIPY)

Qiao

et al. 2018

ChemPhotoChem

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Two aryl-fused BODIPY dyes BF-BDP and NF-BDP were synthesized with benzofuran and naphtho [b]furan fusions on the a,bpositions of the BODIPY skeleton, respectively, resulting in large linear conjugated structures. Both molecules were planar and were characterized as intense deep-red/NIR emitters with emission bands tunable by the solution concentration. Their emission bands were red-shifted to l = 730 and 760 nm in vacuum-deposited films.Fluorophores with photoactivity in the deep-red to NIR region (> 650 nm) are of high interest for several applications, such as chemical sensor, [1] bio-imaging label, [2] and organic photovoltaics. [3][4][5] On one hand, however, their relatively low lying emissive excited states allow more possible non-radiative decay routes, which limit the photoluminescent quantum yields (PLQY) of long-wavelength emission. One the other hand, interaction between photons and electrons that is the principle mechanism in all these applications, high stability and low photo-bleaching effect are required. Thus, continuous research efforts have been put into developing and characterizing new deep-red and NIR fluorophores.4,4-Difluoro-4-borata-3a,4a-diaza-s-indacene, abbreviated as BODIPY, is a popular family of dyes characterized by flexible chemical modifications, tunable absorption/emission band, good photo-stability and high fluorescent efficiency. [6,7] Since the typical photo-active region of a BODIPY chromophore is from 450 to 550 nm, several approaches have been realized to achieve deep-red and NIR absorbing/emitting BODIPYs: (1) introduce "push-pull" strategy by introducing electron donating/withdrawing groups; (2) replace meso-carbon atom by a nitrogen atom to obtain aza-BODIPY; (3) extend the p conjugation system by fusing the dipyrromethene core with aryl moieties. [8] Amongst all these methods, aromatic fusion is a promising strategy for the development of high quality emitters, because the extra rigidity provided by the aromatic fusion structure can enhance the thermal/photo-stability and suppress the non-radiative decay routes via the bond vibration and/or rotation. [9][10][11][12] Several recent examples of BODIPY with aromatic fusion along with either a,b-fusion or b-fusion strategy are illustrated in Scheme 1. [13][14][15][16][17][18] Such fused BODIPYs are generally obtained via complex reaction for aryl-fused pyrrole precursors and/or inter-/intra-molecular ring closure, which usually sacrifices the overall yields of the final BODIPYs.

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Intermolecular states in organic dye dispersions: excimers vs. aggregates

Abstract: Efficient energy transfer in dispersed films of organic dyes to dark excimer sites and highly emissive J-coupled dimers.

Cited by 74 publications

References 41 publications

On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated Boron‐Dipyrromethene (BODIPY) Dyes in Aqueous Solution

On the Aggregation Behaviour and Spectroscopic Properties of Alkylated and Annelated Boron‐Dipyrromethene (BODIPY) Dyes in Aqueous Solution

Chiral Microneedles from an Achiral Bis(boron dipyrromethene): Spontaneous Mirror Symmetry Breaking Leading to a Promising Photoluminescent Organic Material

Highly Efficient Deep‐Red‐ to Near‐Infrared‐Absorbing and Emissive Benzo/Naphtho[b]furan‐Fused Boron Dipyrromethene (BODIPY)

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