Photo-driven near-IR fluorescence switch: synthesis and spectroscopic investigation of squarine-spiropyran dyad

Doddi, Siva; Ramakrishna, Bheerappagari; Venkatesh, Yeduru; Bangal, Prakriti Ranjan

doi:10.1039/c5ra20252c

Cited by 8 publications

(6 citation statements)

References 59 publications

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“…The fluorescence of organic molecules from the first excited to the ground singlet state has a multitude of applications, including in organic light-emitting diodes, 1,2 molecular photoswitches, 3,4 biosensors, 5,6 chemosensors, 7,8 microscopy, 9−11 imaging, 12,13 image-guided surgery, 14,15 phototherapy of cancer, 16,17 etc. Excited states are of interest also for their photoreactivity, which offers conditions for performing unique syntheses.…”

Section: Introductionmentioning

confidence: 99%

“…The fluorescence of organic molecules from the first excited to the ground singlet state has a multitude of applications, including in organic light-emitting diodes, , molecular photoswitches, , biosensors, , chemosensors, , microscopy, − imaging, , image-guided surgery, , phototherapy of cancer, , etc. Excited states are of interest also for their photoreactivity, which offers conditions for performing unique syntheses. , Molecular design in these fields aims to tune the fluorescence properties (e.g., the fluorescence maximum, intensity, bandwidth, or radiation lifetime), while conserving other properties (e.g., what is required to be a medicine/ligand, a sensor, or a valuable technical material).…”

Section: Introductionmentioning

confidence: 99%

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Substituent Effect in the First Excited Singlet State of Monosubstituted Benzenes

2018

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sEDA, pEDA, and cSAR descriptors of the substituent effect were determined for >30 monosubstituted benzenes in the first excited singlet S state at the LC-ωB97XD/aug-cc-pVTZ level. It was found that in the S state, the σ- and π-valence electrons are a bit less and a bit more affected, respectively, than in the S state, but basically, the effect in both states remains the same. In the S and S states, the d(C-X) distances to the substituent's first atom and the ring perimeter correlate with the sEDA and pEDA in the appropriate states, respectively. The energies and the gap of the frontier orbitals in the two states are linearly correlated and for the HOMO(S), LUMO(S), and HOMO(S)-LUMO(S) gap correlate also with the pEDA(S) and cSAR(S) descriptors. In all studied correlations, three similar groups of substituents can be distinguished, for which correlations (i) are very good, (ii) deviate slightly, and (iii) deviate significantly. Comparison of the shape of the HOMO(S) and HOMO(S) orbitals shows that for case (i) HOMO orbitals exhibit almost perfect antisymmetry against the benzene plane, for case (ii) the antisymmetry of HOMO in one of the states is either perturbed or changed, and for case (iii) one HOMO state has σ-character.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Substituent Effect in the First Excited Singlet State of Monosubstituted Benzenes

2018

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“…In the light of structural implications in the isomerization mechanism of spiropyran, − we realized that the introduction of an appropriate photochrome will offer the opportunity to implement an ultrafast photochromic transformations. Keeping this in mind, we have designed ultrafast photochromic unit, OX(5) (Figure ) synthesized from 2,3,3-trimethyl-3 H -indole, 4-formyl benzoic acid, and 2-chloromethyl-4-nitrophenol compounds in three steps.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The fluorescence switching materials allowing us to photoinduced interconversion of photochromic units − with distinct absorption spectra under the influence of optical stimulations are exploited to modulate the emission of complementary fluorophores. − In fact, their use as fluorescent probes has already been explored by us with typical examples. , In the wake of these promising results, we designed a photochrome-fluorophore-photochrome dyad (Chart ) incorporating fluorescent diketopyrrolopyrrole (DPP) component, which emits at 570 nm upon excitation at 500 nm (λ ON ), and a photochromic spiropyran (SP) component, which switches to the corresponding merocyanine (i.e., MC, open conformer) upon irradiation at 330 nm (λ OFF ). The very fast photoinduced transformation of SP into MC (32 ps) encourages the energy transfer pathways (FRET), which induced effective quenching of the DPP fluorescence.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Fluorescence Photoswitch Incorporating Diketopyrrolopyrrole and Benzo[1,3]oxazine

et al. 2017

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With the objective of developing ultrafast fluorescent switch molecules, we have designed and synthesized fluorescence switch molecules incorporating two oxazine photochromes (OX) at the two end of single diketopyrrolopyrrole (DPP) fluorophore giving the shape of the dyad molecule as OX-DPP-OX. For precise characterization, steady-state photophysical properties, acid–base-induced spectroscopic studies and ultrafast transient absorption spectroscopic studies are performed. In acetonitrile (ACN) solution, the benzo[1,3]oxazine ring of studied oxazine derivatives in OX-DPP-OX opens up and reduces the fluorescence intensity of DPP by 66% upon addition of 50 equiv of trifluoroacetic acid (CF3COOH, TFA) and addition of an equivalent amount of base, tetrabutylammonium hydroxide ((C4H9)4NOH, TBAOH), closes the oxazine ring, reverting the fluorescence intensity of the DPP unit back to its original intensity. Likewise, upon 330 nm laser excitation, the oxazine ring opens up in less than 135 ps in ACN solution, reducing the DPP fluorescence by 90%. Both the processes, acidochromic effect and 330 nm laser excitation, generate a 3H-indolium cation, p-nitrophenolate (protonated) and p-nitrophenolate anion, respectively. The photogenerated isomer lives for 1.5–1.9 ns in room temperature and reverts to its original conformer with first-order kinetics. This photochromic dyad tolerates thousands of switching cycles with no sign of degradation. However, the Gibbs free energy of the cationic fragment of their photogenerated isomer and DPP fluorophore is exergonic (ΔG 0 < −0.8) and ultrafast intramolecular electron transfer occurs very fast (in 16 ps time) from DPP moiety to 3H-indolium cation. As a result, the photoinduced transformation of the photochromic component within this dyad results in the effective quenching of the DPP emission. The fluorescence of this photoswitchable compound is modulated on a nanosecond time scale with excellent fatigue resistance under femtosecond (fwhm ∼100 fs) photoexcitation. Thus, the choice of OX as a photochromic component and DPP as fluorescence component can ultimately lead to the development of valuable ultrafast photoswitchable fluorescent probes for designing ultrafast switching devices. Such valuable mechanistic insights into their excitation dynamics can guide the design of novel members of this family of photochromic compounds with improved photochemical properties.

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“…Compared to ultraviolet or visible molecular switches, molecular switches with absorption and emission in the near infrared region (650-900 nm) can minimize interference from background auto-fluorescence, self-absorption and light scattering, and have high potential to be used for information storage, optical communication and especially for the biological sensing. [10][11][12][13][14][15][16] But to date few near-infrared organic molecular switches have been reported owing to their design and synthesis difficulties. [11][12][13][14][15][16] In 2012, Bossi, Sortino, Raymo and coworkers paired a [1,3] oxazine unit to a fluorene ring and the open-ring form of the obtained molecular switch had an absorption maximum centred around 450 nm and an emission maximum centred around 550 nm.…”

Section: Introductionmentioning

confidence: 99%

Design, synthesis and properties of near-infrared molecular switches containing a fluorene ring

et al. 2016

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Three molecular switches containing a fluorene ring were designed and synthesized. The introduction of the amino group substituted fluorene ring resulted in the target molecular switches having some optical properties in the near-infrared region. It was demonstrated that the N-substituents on the fluorene rings and the switch units both had great influence on the molecular switch optical properties including the absorption maximum, absorption intensity and fluorescence quantum yield. The open-ring forms and showed obvious solvatochromic behaviour. The closed-ring forms and showed obvious hydrochromic behaviour in MeCN/water binary solvent systems and acidichromic behaviour in MeCN solution with high reversibility. Especially, the distinct off-on fluorescence signal in the near-infrared region using the stimuli of acid means that the designed compounds have great potential application value in the field of biological sensing.

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Photo-driven near-IR fluorescence switch: synthesis and spectroscopic investigation of squarine-spiropyran dyad

Abstract: Novel NIR fluorescent dyad was synthesized using Squarine derivatives (SQ) and Spiropyran (SP) and characterized. Light driven reversible changes between two isomers of SP modulate the fluorescence of SQ leading to ON/OFF switching behaviors.

Cited by 8 publications

References 59 publications

Substituent Effect in the First Excited Singlet State of Monosubstituted Benzenes

Substituent Effect in the First Excited Singlet State of Monosubstituted Benzenes

Ultrafast Fluorescence Photoswitch Incorporating Diketopyrrolopyrrole and Benzo[1,3]oxazine

Design, synthesis and properties of near-infrared molecular switches containing a fluorene ring

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