Tetrastyryl-BODIPY-Based Dendritic Light Harvester and Estimation of Energy Transfer Efficiency

Metal-free FRET macrocycles of perylenediimide and aza-BODIPY for multifunctional sensing

Two multichromophoric FRET macrocycles M1 [1+1] and M2 [2+2] with red emission (λ_em ∼ 721 nm) composed of perylenediimide (PDI) as the energy donor and aza-BODIPY (ABDP) as the energy acceptor were synthesized by click reaction in a metal-free fashion. M1 and M2 exhibited distinct reversible ratiometric temperature responsive emission with temperature sensitivities of 0.09-0.14% °C^-1 and owing to the redox active chromophores, they showed solution phase redox responsive reversible colour changes.

Aryl/Heteroaryl Substituted Boron-Difluoride Complexes Bearing 2-(Isoquinol-1-yl)pyrrole Ligands Exhibiting High Luminescence Efficiency with a Large Stokes Shift

A series of 2-(isoquinol-1-yl)pyrrole-boron complexes possessing (hetero)aryl substituents on the pyrrole and/or isoquinoline moiety were prepared. These compounds exhibited the fluorescence emission character in both solution and solid state. In most cases, the large Stokes shift and high fluorescence quantum yield in the solution were compatible. Furthermore, the structural diversity allowed the precise tuning of emitting colors from light blue to red with strong emission intensity. The present paper describes their comprehensive optical characteristics dependent on the type and position of the substituted aryl groups by the experimental and computational studies.

Optical and electrochemical effects of triarylamine inclusion to alkoxy BODIPY-based derivatives

Three new triphenylamine-BODIPY dyads BDPT1–3 have been designed and synthesized.

Intramolecular Energy and Electron Transfers in Bodipy Naphthalenediimide Triads

Borondipyrromethene (BDP) naphthalenediimide (NDI) triads (BDP-NDI) and diiodo-BDP derivative (DiiodoBDP-NDI)) were synthesized to study the Förster resonance energy transfer (FRET) and its impact on the triplet state formation and dynamics. In these triads, diiodo-BDP and BDP are the energy donors and NDI is the energy acceptor. Nanosecond transient absorption spectra of triads indicated that triplet state is localized on NDI moiety, either by selective photoexcitation of the Diiodo-BDP or NDI unit. The intersystem crossing (ISC) is attributed to intramolecular heavy atom effect. The triplet state quantum yield was found to be 54% with a lifetime of 38 μs. However, no triplet state is observed for BDP-NDI system either by exciting BDP or NDI unit. Thus, we confirmed that charge recombination does not produce a triplet state. Interestingly, DiiodoBDP-NDI can be used as broadband excitable (500-620 nm) triplet photosensitizer, and high triplet-triplet annihilation (TTA) upconversion quantum yield of Φ_UC = 2.8% was observed with 9,10-bis(phenylethynyl)-anthracene (BPEA) as a triplet acceptor/emitter.

Exploiting the benefit of S0→ T1 excitation in triplet-triplet annihilation upconversion to attain large anti-stokes shifts: tuning the triplet state lifetime of a tris(2,2'-bipyridine) osmium(ii) complex

Os(ii) complexes are particularly interesting for triplet-triplet annihilation (TTA) upconversion, due to the strong direct S₀→ T₁ photoexcitation, as in this way, energy loss is minimized and large anti-Stokes shift can be achieved for TTA upconversion. However, Os(bpy)₃ has an intrinsic short T₁ state lifetime (56 ns), which is detrimental for the intermolecular triplet-triplet energy transfer (TTET), one of the crucial steps in TTA upconversion. In order to prolong the triplet state lifetime, we prepared an Os(ii) tris(bpy) complex with a Bodipy moiety attached, so that an extended T₁ state lifetime is achieved by excited state electronic configuration mixing or triplet state equilibrium between the coordination center-localized state (³MLCT state) and Bodipy ligand-localized state (³IL state). With steady-state and time-resolved transient absorption/emission spectroscopy, we proved that the ³MLCT is slightly above the ³IL state (by 0.05 eV), and the triplet state lifetime was prolonged by 31-fold (from 56 ns to 1.73 μs). The TTA upconversion quantum yield was increased by 4-fold as compared to that of the unsubstituted Os(ii) complex.

Synthesis and Properties of Covalently Linked AzaBODIPY-BODIPY Dyads and AzaBODIPY-(BODIPY)2 Triads

The azaBODIPYs containing one and two formyl functional groups on the 1,7-aryl groups present at the azaBODIPY core were synthesized over sequence of steps and characterized by mass, NMR, absorption, and electrochemical techniques. The monoformylated and diformylated azaBODIPYs are very useful synthons to prepare a wide variety of new fluorescent compounds. The mono- and diformylated azaBODIPYs were treated with pyrrole under mild acidic conditions followed by column chromatographic purification to afford azaBODIPYs appended with one and two dipyrromethanyl groups. The dipyrramethanyl groups of azaBODIPYs were oxidized with DDQ and complexed with BF₃·Et₂O to obtain covalently linked azaBODIPY-BODIPY dyads and azaBODIPY-(BODIPY)₂ triads. The dyads and triads were characterized in detail by HR-MS, 1D and 2D NMR, absorption, fluorescence, and electrochemical techniques and the structure of one of the triads was deduced by X-ray crystallography. The crystal structure of azaBODIPY-(BODIPY)₂ triad revealed that the two BODIPY units were in perpendicular orientation with azaBODIPY unit. The absorption and electrochemical studies indicated a weak interaction among the BODIPY and azaBODIPY moieties and the moieties retain their independent characteristic features in dyads and triads. The preliminary fluorescence studies supported an efficient energy transfer from BODIPY unit(s) to azaBODIPY unit in dyads and triads.

Demonstrating the role of anchoring functionality in interfacial electron transfer dynamics in the newly synthesized BODIPY–TiO2 nanostructure composite

Scheme illustrating the extent of coupling and charge recombination dynamics between BODIPY and NS-TiO₂ anchoring through the catechol and resorcinol binding group.

The Influence of the π-Conjugated Spacer on Photophysical Properties of Difluoroboranyls Derived from Amides Carrying a Donor Group

A series of difluoroboranyls derived from amides carrying a variable π-conjugated spacer between the electron-donating (D) and electron-accepting (A) groups was synthesized and characterized with (1)H, (11)B, (13)C, (15)N, and (19)F NMR, electronic absorption, fluorescence spectroscopies, and first-principle calculations. The D-to-A distance in the series varied from 1.5 to 4.5 Å, causing bathochromic shifts of both the absorption and fluorescence maxima by more than 120 and 213 nm, respectively. These trends are rationalized by quantum-mechanical calculations that allow for quantification of the charge-transfer distance. Theoretical calculations were also performed to determine the vibronic couplings and thus to reproduce the experimental band shapes.

BODIPY based self-healing fluorescent gel formation via acylhydrazone linkage

Polymeric BODIPY derivatives with reactive functional groups undergo reversible formation of covalent bonds leading to self-healing properties.

Novel aluminum–BODIPY dyads: intriguing dual-emission via photoinduced energy transfer

Three novel BODIPY-based heterodinuclear complexes were prepared and especially, salen-based aluminum–BODIPY dyads exhibited intramolecularly significant photoinduced energy transfer from aluminum–salen to the BODIPY group.

BODIPY-containing porous organic polymers for gas adsorption

BODIPY-containing microporous organic polymers were synthesized via a Sonogashira–Hagihara coupling reaction of a BODIPY derivative and a range of aryl–alkyne monomers.

Photoinduced charge separation in wide-band capturing, multi-modular bis(donor styryl)BODIPY–fullerene systems

A new series of multi-modular, wide-band capturing donor–acceptor systems capable of exhibiting photoinduced charge separation have been designed, synthesized and characterized using various techniques.

Synthesis of energy transfer cassettes via click and Suzuki–Miyaura cross coupling reactions

Novel cassettes capable of energy transfer involving simple synthetic methodsviz., click reaction at C-8 position and palladium catalyzed Suzuki–Miyaura cross coupling at C-6 position of imidazo[1,2-a]pyrazine, have been represented.

Multistimuli Sensitive Behavior of Novel Bodipy-Involved Pillar[5]arene-Based Fluorescent [2]Rotaxane and Its Supramolecular Gel

Fluorescent [2]rotaxane BC12P5 is successfully constructed with 1,4-diethoxypillar[5]arene as wheel over a long alkyl axle with Bodipy chromophore as one stopper for the first time. NMR spectra clearly reveal its molecular shuttle nature triggered by multiple external stimuli including solvent polarity and temperature. In particular, the fluorescence nature introduced into [2]rotaxane BC12P5 renders it a good sensor for the external stimuli. Nevertheless, the supramolecular gel successfully fabricated from this novel rotaxane system via self-assembly in dimethyl sulfoxide (DMSO) also shows reversible gel-sol phase transition upon multiple external stimuli such as heating/cooling, shaking/resting, or the addition of different anions. Interestingly, exposure of the supramolecular gel film to HCl or ammonia vapor induces the change in the film fluorescence intensity, endowing this system with a potential application in gas detecting.

Fast responding and selective near-IR Bodipy dye for hydrogen sulfide sensing

A Bodipy based, highly selective probe for hydrogen sulfide has been designed, synthesized and demonstrated to detect H2S in living cells. In this design, the reduction of two arylazido groups change the charge transfer characteristics of the 3,5-distyryl substituents on the Bodipy core, producing a 20 nm bathochromic spectral shift in the absorption band, and quenching of the emission by 85% compared to the original intensity, through photoinduced electron transfer.

Deep-red emissive BODIPY-chlorin arrays excitable with green and red wavelengths

We report here the synthesis and characterization of BODIPY-chlorin arrays containing a chlorin subunit, with tunable deep-red (641-685 nm) emission, and one or two BODIPY moieties, absorbing at 504 nm. Two types of arrays were examined: one where BODIPY moieties are attached through a phenylacetylene linker at the 13- or 3,13-positions of chlorin, and a second type where BODIPY is attached at the 10-position of chlorin through an amide linker. Each of the examined arrays exhibits an efficient (≥0.80) energy transfer from BODIPY to the chlorin moiety in both toluene and DMF and exhibits intense fluorescence of chlorin upon excitation of BODIPY at ∼500 nm. Therefore, the effective Stokes shift in such arrays is in the range of 140-180 nm. Dyads with BODIPY attached at the 10-position of chlorin exhibit a bright fluorescence in a range of solvents with different polarities (i.e., toluene, MeOH, DMF, and DMSO). In contrast to this, some of the arrays in which BODIPY is attached at the 3- or at both 3,13-positons of chlorin exhibit significant reduction of fluorescence in polar solvents. Overall, dyads where BODIPY is attached at the 10-position of chlorin exhibit ∼5-fold brighter fluorescence than corresponding chlorin monomers, upon excitation at 500 nm.

Synthesis and fluorescence properties of a boron-dipyrrin functionalized perylenediimide derivative

A dual-channel dendritic chemosensor for Hg²⁺ with high FRET efficiency was designed and synthesized.

Halogenated boron-dipyrromethenes: synthesis, properties and applications

Synthesis and properties of halogenated boron-dipyrromethenes and their applications in developing various BODIPY systems are described in this review.

A facile and high-yield formation of dipyrrin-boronic acid dyads and triads: a light-harvesting system in the visible region based on the efficient energy transfer

Artificial light-harvesting systems, Ar,O-BODIPY dyads and triads conjugated with a light harvester, were synthesized in high yield by the reaction of an N₂O₂-type dipyrrin with boronic acids.

Maximizing the thiol-activated photodynamic and fluorescence imaging functionalities of theranostic reagents by modularization of Bodipy-based dyad triplet photosensitizers

The fluorescence imaging and singlet oxygen production ability of thiol-cleavable triplet photosensitizers was maximized by disintegration of the functionalities.

The triplet excited state of Bodipy: formation, modulation and application

The accessing of the triplet excited state of one of the most popular fluorophores, boron-dipyrromethene (Bodipy), was summarized.

Bodipy/dipyridylamino-based “turn-on” fluorescent chemosensor for trivalent chromium cations: characterization and photophysical properties

{{3,5-Bis[4,4-difluoro,8-(2,6-diethyl,1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene)]}}phenyl-N,N-di(pyridin-2-yl)benzamide (Bodipy-DPy) was designed as an efficient fluorescent chemosensor for Cr(iii).

A fluorescent “turn on” chemosensor based on Bodipy–anthraquinone for Al(iii) ions: synthesis and complexation/spectroscopic studies

A fluorescent “turn on” Al(iii) chemosensor based-on bodipy–anthraquinone with two triazole ring was prepared and studied for its complexation and spectroscopic properties.

Synthesis and use of “clickable” bay-region tetrasubstituted perylene tetracarboxylic tetraesters and a perylene monoimide diester as energy acceptors

Novel perylene derivatives are ready to be used as functional energy acceptors in light-harvesting systems.

Switching of the triplet excited state of styryl 2,6-diiodo-bodipy and its application in acid-activatable singlet oxygen photosensitizing

IodoBodipy-styrylBodipy dyads triplet photosensitizers were prepared (B-1 and B-2) which contain acid-responsive moiety. Both compounds show broadband visible light absorption, due to the resonance energy transfer (RET) between the two different visible light-harvesting Bodipy units. The photophysical properties of the dyads were studied with steady-state and nanosecond time-resolved transient absorption spectroscopy. The production of triplet excited state is switched ON or OFF by protonation/deprotonation of the amino group in the dyads. In the neutral form, the excited state is short-lived (<10 ns) and no singlet oxygen ((1)O2) photosensitizing was observed. Upon protonation, a long-lived triplet excited state was observed (τT = 3.1 μs) and the (1)O2 quantum yield (ΦΔ) is up to 73.8%. The energy levels of the components of the dyads were changed upon protonation and this energy level tuning exerts significant influence on the triplet state property of the dyad. Acid-activated shuffling of the localization of the triplet excited state between two components of a dyad was observed. Furthermore, we observed a rare example that a chromophore giving shorter absorption wavelength is acting as the singlet energy acceptor in RET. The experimental results were rationalized by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations.