Multiple luminescence from borohydridobis(triphenylphosphine)copper(I)

Segers, Donald P.; DeArmond, M. Keith; Grutsch, Paul A.; Kutal, Charles

doi:10.1021/ic00186a032

Cited by 36 publications

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“…The absorption spectra of all the phosphines show a band between 275 nm and 400 nm, which undergoes a bathochromic shift as the oligothienyl length increases (Figure ). In addition, a shoulder is observed at ∼250 nm, which is analogous to the n→π* transition in triphenylphosphine at 263 nm. − The data are collected in Table . The presence of the phosphine group results in red-shifting of the absorbance bands, relative to the unsubstituted thiophene oligomers ( T (231 nm), T 2 (303 nm), and T 3 (354 nm)) .…”

Section: Resultsmentioning

confidence: 99%

“…In addition, a shoulder is observed at ∼250 nm, which is analogous to the nfπ* transition in triphenylphosphine at 263 nm. [24][25][26] The data are collected in Table 1. The presence of the phosphine group results in red-shifting of the absorbance bands, relative to the unsubstituted thiophene oligomers (T (231 nm), T 2 (303 nm), and T 3 (354 nm)).…”

Section: Resultsmentioning

confidence: 99%

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Spectroscopic Study of Phosphine-Substituted Oligothiophenes

Stott

Wolf

2004

J. Phys. Chem. B

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The spectroscopic behavior (solution and solid-state absorption and emission) of a series of mono-(diphenylphosphino) and bis-(diphenylphosphino) R-substituted oligothiophenes varying in length from one to three thienyl rings is described. The absorption spectra red-shift with increasing oligomer length, and the spectra of the bisphosphines are red-shifted, relative to the monophosphines that contain the same number of thienyl groups. In solution, emission from the mono-and bithienyl compounds is broad and shows a large Stokes shift, attributed to a planar excited state due to the nfπ* nature of the excitation. Emission from the terthienyl compounds shows a much smaller Stokes shift and is attributed to a thienyl-based πfπ* transition. In the solid state, similar effects are observed in both absorption and emission spectra. Density functional theory (DFT) calculations show that the contribution of the P lone pair to the highest occupied molecular orbital (HOMO) diminishes as the oligomer length increases, supporting the experimental results. IntroductionConjugated oligomers and polymers are organic materials with many interesting properties, including electronic conductivity, luminescence, and color. 1 Pendant metal groups, which can be attached using several different coordinating groups, may be used to modify the electronic and optical properties of these materials. [2][3][4][5][6][7][8][9][10][11] Our group has investigated the use of phosphine substituents as ligating groups, 12-16 which is an approach driven both by the versatility of phosphines in binding a wide variety of metals 17 and the benefit of having only a single atom (P) between the metal and conjugated backbone, facilitating strong electronic interactions. It is therefore of interest to understand the electronic behavior of phosphine-substituted oligothiophenes prior to the coordination of a metal, because this is important to help build an understanding of the behavior of corresponding metal complexes.The electronic effects of a range of substituents both in the terminal (R) position and the internal ( ) position of thiophenes and oligothiophenes have been studied. 18 However, no systematic study of the influence of phosphine substituents on the electronic properties of the conjugated backbone exists. Diarylamino-substituted oligothiophenes, ranging from one to six rings in length, have been prepared. 19 These compounds show strong bathochromic shifts, relative to the parent oligomers in both absorption and emission spectra; in addition, because nitrogen and phosphorus are Group 15 congeners, it is interesting to compare these compounds to the phosphino analogues. Here, we report the absorption and emission spectra of the series of monosubstituted and disubstituted oligothiophenes shown in Chart 1, both in solution and in the solid state as thin films. The disubstituted thiophenes are of interest because of the possibility of binding metals to the ends of these ligands, which is relevant to "molecular wire" studies with these conjugated compound...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Spectroscopic Study of Phosphine-Substituted Oligothiophenes

Stott

Wolf

2004

J. Phys. Chem. B

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“…The charge-transfer luminescence of copper(I) to π* orbitals in phenanthroline rings occurs in the red section of the visible region extending into the near-IR , In the case of the charge transfer from Cu(I) to π* orbitals in the pyrazolyl rings, the lowest energy transition would be from a t 2 d orbital (in tetrahedral symmetry) to the π* orbital on the pyrazolyl ring. Because the Tp ligand is not considered to be a good acceptor, copper to Tp chage transfer might be expected to occur at higher energies .…”

Section: Discussionmentioning

confidence: 99%

Ligand to Ligand Charge Transfer in (Hydrotris(pyrazolyl)borato)(triphenylarsine)copper(I)

2000

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Emission and UV-vis absorption spectra of (hydrotris(pyrazolyl)borato)(triphenylarsine)copper(I), (CuTpAsPh3), (hydrotris(pyrazolyl)borato)(triethylamine)copper(I), (CuTpNEt3), and (hydrotris(pyrazolyl)borato)(triphenylphosphine)copper(I), (CuTpPPh3), are reported. The spectra of the arsine complex contain low-energy bands (with a band maximum at 16,500 cm(-1) in emission and a weak shoulder centered at about 25,000 cm(-1) in absorption) that are not present in the corresponding spectra of the amine or phosphine complexes. The lowest energy electronic transition is assigned to ligand to ligand charge transfer (LLCT) with some contribution from the metal. This assignment is consistent with PM3(tm) molecular orbital calculations that show the HOMO to consist primarily of pi orbitals on the Tp ligand (with some metal orbital character) and the LUMO to be primarily antibonding orbitals on the AsPh3 ligand (also with some metal orbital character). The absorption shoulder shows a strong negative solvatochromism, indicative of a reversal or rotation of electric dipole upon excitation, and consistent with a LLCT. The trends in the energies of the electronic transitions and the role of the metal on the LLCT are discussed.

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“…As expected, compounds 2 and 3, which have no significant interactions between the gold centers, show no strong emission, even at 77 K. The weak blue emission centered at 473 nm with excitation at 330 nm, which is observed at liquid-N2 temperatures for compound 2, has been assigned as transitions associated with the phenyl groups on the tetraphenylborate anion and the phenol ligand similar to that observed for the PPh.3 ligand. 23…”

Section: Discussionmentioning

confidence: 99%