Relationship between π-Conjugation Size and Electronic Absorption Spectrum:  Novel π-Conjugation Size Dependence of Indoaniline Dyes

Adachi, Masafumi; Murata, Yukichi

doi:10.1021/jp972965j

Cited by 24 publications

(11 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is also noted that the LUMO energies increase proportionately with the increase in the size of the π-surface but inversely with the observed reactivity of the complexes. Preceding studies have associated this phenomenon with molecular distortions (tetracyano-p-quinodimethane), 84 an increase in total antibonding character of the orbitals (in indoanilines and anhydrides) 85,86 or an increased localization of the π* orbital on the complexes, 87 which is evident with the LUMO mappings in these studies. A direct relationship is noticed between the reactivity trend and HOMO-LUMO energy gaps as well as the electrophilicity indices (see Table 1).…”

Section: Discussionmentioning

confidence: 68%

Kinetic and mechanistic studies of 1,3-bis(2-pyridylimino)isoindolate Pt(ii) derivatives. Experimental and new computational approach

Wekesa

Jaganyi

2014

Dalton Trans.

View full text Add to dashboard Cite

The rate of substitution of the chloride ligand by three bio-relevant nucleophiles, thiourea (Tu), N,N-dimethylthiourea (Dmtu) and N,N,N,N-tetramethylthiourea (Tmtu), in the complexes: 1,3-bis(2-pyridylimino)isoindoline platinum(II) chloride (Pt2), 1,3-bis(2-pyridylimino)benz(f)isoindoline platinum(II) chloride (Pt3) and 1,3-bis(1-isoquinolylimino)isoindoline platinum(II) complex (Pt4) was investigated under pseudo first-order conditions as a function of concentration and temperature using stopped-flow and UV-Visible spectrophotometry. Computational modeled data of bis(pyridylimino)3,4-pyrrolate platinum(II) chloride (Pt1) were incorporated in the study for comparison. The observed pseudo first-order rate constants for substitution reactions obey the rate law kobs = k2[Nu]. High negative activation entropies and second-order kinetics for the displacement reactions all support an associative mode of activation. The reactivity is dependent on stabilization of the LUMO energy and inversely proportional to the number of phenyl rings added irrespective of the site of attachment. The electron density on the ligand moiety plays a significant role in the substitution behavior of the platinum(II) complexes, as supported by DFT descriptors {electrophilicity index (ω) and chemical hardness (η)}.

show abstract

Section: Discussionmentioning

confidence: 68%

Kinetic and mechanistic studies of 1,3-bis(2-pyridylimino)isoindolate Pt(ii) derivatives. Experimental and new computational approach

Wekesa

Jaganyi

2014

Dalton Trans.

View full text Add to dashboard Cite

show abstract

“…On the other hand, the structural entanglement of these PIs is expected to be sensitive to the surrounding environment, especially to the solvent polarity. − When the electrons of a solvent can rearrange to stabilize the excited states of a molecule, the energy difference between the electronic levels of the molecule becomes lower and the absorption moves to a higher wavelength. This is also true for these azo-polymers in high polar solvents such as DMF that better stabilizes the dipolar species compared to those in less polar solvents, like CHCl 3 .…”

Section: Resultsmentioning

confidence: 99%

Structural Chemistry-Assisted Strategy toward Fast Cis–Trans Photo/Thermal Isomerization Switch of Novel Azo-Naphthalene-Based Polyimides

Constantin¹,

Sava²,

Damaceanu³

2021

Macromolecules

View full text Add to dashboard Cite

Pursuing the research toward smart material development, novel azopolyimides containing highly photoresponsive azo-naphthalene moieties are synthesized and fully characterized toward efficient, fast, and stable cis−trans photo/ thermal isomerization switch. To this aim, a novel triphenylmethane diamine carrying a photochromic receptor is prepared and used in polycondensation with aromatic dianhydrides. Insights into molecular weights and thermal, optical, and electrochemical characteristics are employed to accomplish basic characterizations. To prove the switching characteristics insufficiently explored for polyimides (PIs), trans−cis and cis−trans photo/thermal isomerizations are surveyed by UV−vis and 1 H NMR investigations. UV− vis absorption studies reveal unprecedented fast trans−cis switches (47−130 s) through rotation mechanism in dimethylformamide, with one of the highest efficiencies reported nowadays for PIs, up to 90.2%. Slower thermal cis−trans relaxation is experienced owing to a nonpolarity-assisted inversion mechanism. After 15 repetitive trans−cis−trans switching cycles, an excellent stability up to 96.29% is recorded. The PI films obtained without any dilution in solid state reach the photostationary state after longer irradiation time but with excellent efficiency, up to 75.7%, and trans−cis−trans conversion stability, up to 92.68%, after 10 cycles. The photoisomerization studies are completed by 1 H NMR that evidences spectral profiles change during irradiation. Perspective optoelectronic applications that demand photocontrollable functions are foreseen.

show abstract

“…In the reported work on benzannulation on organic compounds, either hypsochromic or bathochromic shifts in the absorption and emission spectra have been observed relying on the benzannulation site. − Despite finding this unusual phenomenon in small organic molecules, examples featuring the impacts of varied benzannulation site at the ligands on organometallic complexes are still rare. , In seeking a better understanding of the influences of benzannulation site at the ligands on the photophysical properties of the complexes, the seminal report by Thompson and Gordon on the (N^N^N)PtCl derivatives has intrigued our interest in other heavy transition-metal complexes, such as the Ir(III) complexes. In our previous work, we explored a series of cyclometalated monocationic Ir(III) complexes employing 1,2-diphenyl-9 H -pyreno[4,5- d ]imidazole as the C^N ligands, and 2-(pyridin-2-yl)quinoline and its derivatives as the N^N ligand .…”

Section: Introductionmentioning

confidence: 99%

Impact of Benzannulation Site at the Diimine (N^N) Ligand on the Excited-State Properties and Reverse Saturable Absorption of Biscyclometalated Iridium(III) Complexes

et al. 2019

View full text Add to dashboard Cite

Ten biscyclometalated monocationic Ir(III) complexes were synthesized and studied to elucidate the effects of extending π-conjugation of the diimine ligand (N^N = 2,2′-bipyridine in, and 1,1′-biisoquinoline in Ir10) via benzannulation at 2,2′-bipyridine on the excited-state properties and reverse saturable absorption (RSA) of these complexes. Either a bathochromic or a hypsochromic shift of the charge-transfer absorption band and emission spectrum was observed depending on the benzannulation site at the 2,2′-bipyridine ligand. Benzannulation at the 3,4-/3′,4′-position or 5,6-/5′,6′-position of 2,2′-bipyridine ligand or at the 6,7-position of the quinoline ring on the N^N ligand caused red-shifted charge-transfer absorption band and emission band for complexes Ir2, Ir8, Ir10 vs Ir1 and Ir3 vs Ir2, while benzannulation at the 4,5-/4′,5′-position of 2,2′-bipyridine ligand or at the 7,8-position of the quinoline ring on the N^N ligand induced a blue shift of the charge-transfer absorption and emission bands for complex Ir9 vs Ir1 and Ir4 vs Ir2. However, benzannulation at the 2,2′,3,3′-position of 2,2′-bipyridine or 5,6-position of phenanthroline ligand had no impact on the energy of the chargetransfer absorption band and emission band of complexes Ir5−Ir7 compared with those of Ir1. The observed phenomenon was explained by the frontier molecular orbital (FMO) symmetry analysis. Site-dependent benzannulation also impacted the spectral feature and intensity of the triplet transient absorption spectra and lifetimes drastically. Consequently, the RSA strength of these complexes varied with a trend of Ir7 > Ir5 ≈ Ir6 ≈ Ir1 > Ir3 > Ir2 > Ir10 > Ir4 > Ir8 > Ir9 at 532 nm for 4.1 ns laser pulses.

show abstract

Relationship between π-Conjugation Size and Electronic Absorption Spectrum: Novel π-Conjugation Size Dependence of Indoaniline Dyes

Cited by 24 publications

References 37 publications

Kinetic and mechanistic studies of 1,3-bis(2-pyridylimino)isoindolate Pt(ii) derivatives. Experimental and new computational approach

Kinetic and mechanistic studies of 1,3-bis(2-pyridylimino)isoindolate Pt(ii) derivatives. Experimental and new computational approach

Structural Chemistry-Assisted Strategy toward Fast Cis–Trans Photo/Thermal Isomerization Switch of Novel Azo-Naphthalene-Based Polyimides

Impact of Benzannulation Site at the Diimine (N^N) Ligand on the Excited-State Properties and Reverse Saturable Absorption of Biscyclometalated Iridium(III) Complexes

Contact Info

Product

Resources

About