Triarylmethane Dye Photochromism: Spectroscopy and Photochemistry of Brilliant Green Leucocyanide

Geiger, Margaret W.; Turro, Nicholas J.; Waddell, Walter H.

doi:10.1111/j.1751-1097.1977.tb07418.x

Cited by 15 publications

(19 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such electronic decoupling of structural components has been generally proven for spiropyrans 43 and for various leuco forms of triarylmethanes, including malachite green leuconitrile (MGCN). 28,44,45 The first and the second absorption bands in MGL are similar to the first two bands in N,N 0 -dimethyl-p-toluidine (DMT, i.e. methyl substituted DMA) which models each of the two chromophores attached to phthalide, and on that basis have been assigned to absorption transitions occurring within isolated dimethylaniline units.…”

Section: Absorption Spectramentioning

confidence: 81%

Photoinduced electron transfer in malachite green lactoneDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

Karpiuk

2003

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The spectroscopy and photophysics of malachite green lactone (MGL), a lactonic form of the well-know malachite green dye, have been studied as functions of solvent polarity in aprotic and protic solvents at different temperatures in solution and in glass. It has been found that MGL photophysics substantially differs from that of other malachite green leucoderivatives (e.g. leuconitrile, leucohydroxide or halides). In aprotic solvents ultrafast intramolecular electron transfer (estimated t ET 130 fs) between MGL structural components (from initially excited insulated dimethylaniline, DMA, to phthalide, Pd) results in formation of a highly polar (25.0 D) intramolecular CT state which then emits fluorescence. The dynamics of the primary ET are determined mainly by intramolecular vibrational motions and not by the solvation process. The polar nature of the emitting state was verified with the solvatochromic method, and S n S 1 transient absorption spectra prove that charge separation results in formation of DMA radical cation in MGL. The separation of charges is maintained in the charge transfer triplet state, which lies below the local triplet levels of MGL structural components, making MGL a unique candidate for studying both CT triplet state and CT-singlet-triplet dynamics. The electronic structure of the 1 CT state stabilizes charge separation in moderately polar solvents (e.g. F fl and t fl in butyl acetate (BA) are 0.12 and 23.8 ns, respectively) and no evidence has been found for photodissociation of C-O bond in lactone ring in aprotic solvents, which is the dominant photoprocess in malachite green leuconitrile or halides. Further increase of solvent polarity results in dramatic enhancement of MGL nonradiative deactivation from the 1 CT state (increase in k nr by two orders of magnitude on going from BA to ACN) pointing to a solvent polarity-driven deactivation channel. The strong dependence of CT fluorescence quantum yield on CT transition energy found in supercooled and in glassy butyronitrile (BTN), where conformational motions are restricted, suggests that the nonradiative decay is (i) not related to conformational changes and (ii) consists in enhancement of nonradiative return electron transfer (direct radiationless charge recombination), which is proven by the good linear correlation between ln k nr and ñ n fl in more polar solvents (energy gap law). The large temperature-dependent blue shift of the fluorescence maximum in BTN below the melting point (rigidochromism) makes MGL a very sensitive probe for studying reorientation polarization in rigid and semi-rigid supercooled media.y Dedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

show abstract

Section: Absorption Spectramentioning

confidence: 81%

Photoinduced electron transfer in malachite green lactoneDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

Karpiuk

2003

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…While various radical-dissociation-type photochromic molecules which show the photoinduced homolysis have been reported so far, [11][12][13][14][29][30][31][32] photochromic molecules that show photoinduced heterolysis are still scarce. [2,33,34] Because CT forms generated by photoinduced heterolysis have large dipole moments and different chemical reactivities, these fast photochromic materials can be applied to photocatalysts, [35] photoinduced aggregations, and phase separations. [36] However, the lifetime of the CT state of PTIC is too short (picoseconds) to apply it to photofunctional materials.…”

Section: Introductionmentioning

confidence: 99%

Extending the Lifetimes of Charge Transfer States Generated by Photoinduced Heterolysis of Photochromic Radical Complexes

et al. 2021

View full text Add to dashboard Cite

Novel fast photochromic phenothiazine-imidazolyl radical complex (PTIC) derivatives were developed, which form the charge transfer (CT) states and the neutral openshell transient species in a stepwise manner upon light irradiation. The lifetimes of the CT states were extended from picoseconds to hundreds of picoseconds by the substitution of a triphenylamine group on the phenothiazine moiety. The CT forms have different optical properties and chemical reactivities from those of the neutral open-shell transient species. Therefore, the developments of fast T-type photochromic molecules that generate long-lived CT forms are important for expanding potential applications of fast photoswitching materials.

show abstract

“…While the homolytic bond dissociation is the major process for photoinduced σ-bond dissociations, there are several compounds that show the photoinduced heterolysis. − Triarylmethanes and diphenylmethyl halides are well-known examples that show both homolysis and heterolysis depending on the environments and substituents. Systematic investigations by the Turro, Hertz, and Peter groups ,, suggest that the photoinduced heterolysis is likely to occur when the potential energy of the S n (σ, σ*) state, which has the zwitterionic character, decreases by dissolving in polar solvents or by introducing substituents stabilizing the zwitterion.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photochromic Radical Complexes That Show Heterolytic Bond Dissociation

et al. 2020

View full text Add to dashboard Cite

Photochromic materials have been widely used in various research fields because of their variety of photoswitching properties based on various molecular frameworks and bond breaking processes, such as homolysis and heterolysis. However, while a number of photochromic molecular frameworks have been reported so far, there are few reports on photochromic molecular frameworks that show both homolysis and heterolysis depending on the substituents with high durability. The biradicals and zwitterions generated by homolysis and heterolysis have different physical and chemical properties and different potential applications. Therefore, the rational photochromic molecular design to control the bond dissociation in the excited state on demand expands the versatility for photoswitch materials beyond the conventional photochromic molecular frameworks. In this study, we synthesized novel photochromic molecules based on the framework of a radical-dissociationtype photochromic molecule: phenoxyl-imidazolyl radical complex (PIC). While the conventional PIC shows the photoinduced homolysis, the substitution of a strong electron-donating moiety to the phenoxyl moiety enables the bond dissociation process to be switched from homolysis to heterolysis. This study gives a strategy for controlling the bond dissociation process of the excited state of photochromic systems, and the strategy enables us to develop further novel radical and zwitterionic photoswitches.

show abstract

Triarylmethane Dye Photochromism: Spectroscopy and Photochemistry of Brilliant Green Leucocyanide

Cited by 15 publications

References 22 publications

Photoinduced electron transfer in malachite green lactoneDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

Photoinduced electron transfer in malachite green lactoneDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

Extending the Lifetimes of Charge Transfer States Generated by Photoinduced Heterolysis of Photochromic Radical Complexes

Photochromic Radical Complexes That Show Heterolytic Bond Dissociation

Contact Info

Product

Resources

About