Bis(stilbenyl)squaraines — Novel pigments with extended conjugation

Meier, Herbert; Dullweber, Uta

doi:10.1016/0040-4039(95)02414-x

Cited by 37 publications

(13 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, in the design of dye‐sensitized solar cells with enhanced light harvesting capabilities in the NIR ,,. Such interest has motivated the detailed theoretical and experimental characterization of their singlet‐singlet transitions,,,, and it is well known that the presence of donor or acceptor moieties on the backbone, π‐conjugation,,,, or heavy atoms may lead to modifications in the absorption energy. On the other hand, information about their lowest‐lying triplet state is much scarcer.…”

Section: Introductionmentioning

confidence: 99%

Potential Use of Squarates and Croconates as Singlet Fission Sensitizers

2018

View full text Add to dashboard Cite

The geometrical and electronic structures of 44 squarate and croconate derivatives are computationally studied by quantum chemistry methods, in the pursuit of new singlet fission sensitizers. A non-negligible singlet open-shell diradical character is observed for most of the studied molecules, which can be controlled through chemical substitution as well as by the size of the central ring. Such a diradical character is related to small singlet-triplet energy gaps, facilitating the accomplishment of the singlet fission energetic requirements. In general, the present results indicate that squarates hold superior singlet fission capabilities than croconates, although we have identified several derivatives within both families as promising singlet fission sensitizers.

show abstract

Section: Introductionmentioning

confidence: 99%

Potential Use of Squarates and Croconates as Singlet Fission Sensitizers

2018

View full text Add to dashboard Cite

show abstract

“…Squaraine and croconine with C–N bonding are having absorption in visible region ranging from 300 to 600 nm with extinction coefficient ≥10 4 cm −1 M −1 . Whereas, C–C bonded dyes show absorption in the range of 600 to 1200 nm (visible‐NIR region) with high extinction coefficient ≥10 5 cm −1 M −1 …”

Section: Introductionmentioning

confidence: 99%

“…In general, to improve absorption towards longer wavelength, it requires small highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) gap (HLG). The decrease in HLG can be obtained either by increasing π ‐conjugation or by introducing a heavy element in the back bone . The increase in π ‐conjugation offered limited success, while insertion of a heavy element in back bone makes the labile molecular frame.…”

Section: Introductionmentioning

confidence: 99%

Visible absorbing symmetrical squaraine and croconine dye derivatives: A comparative computational study

Tripathi

Promila

2016

J. Phys. Org. Chem.

View full text Add to dashboard Cite

Visible absorbing C-N bonding squaraines (SQ1-SQ5) and croconines (CR1-CR5) with an increase in conjugation at donor groups and heteroaromatic donor substituents have been studied by density functional theory and time-dependent density functional theory methodologies. In these molecules, croconines always have absorption nearly 100-nm red shift than its corresponding squaraines (it is in consistent with C-C bonding, near infrared absorbing squaraine and croconines). The reason behind this drastic red shift, by changing the central acceptor of 4-membered squarate ring with 5-membered croconate ring, has been analyzed by considering the concept of diradical character and variation in central C-C-C angle. It is also observed that within the same series of molecules (either in squaraine or in croconines), with an increase in donor capacity (conjugation), absorption increases towards longer wavelength region because of destabilization of HOMO and stabilization of LUMO levels. A small blue shift was observed for heteroaromatic donor groups when compared with aromatic donor group.

show abstract

“…[38][39][40] Conventionally, SQ dyes and CR dyes were known as D-A-D type of systems and it was believed that the donor (from the side substituent) and acceptor (central four-membered/vemembered ring, respectively, and the carbonyl oxygens) abilities will inuence their absorption spectrum. [41][42][43][44][45][46] In contrast, from our earlier calculations through high level ab initio and density functional theory (DFT) calculations, the biradicaloid character (BRC) of these dyes has been unveiled and it has been shown that the orbital interactions and the C-C-C angle in the central ring of SQ/CR are playing a major role in their near infrared (NIR) absorption rather than D-A-D phenomenon. [47][48][49] In the same way, the poor performance of LC and CAM functionals for the SQ and CR dye derivatives has been already reported by our group whereas the symmetry adapted cluster conguration interaction (SAC-CI) method correctly describes the electronic transitions in these BRC systems.…”

Section: Introductionmentioning

confidence: 99%