Picosecond Infrared Spectrum of 4-(Pyrrol-1-yl)benzonitrile:  Structure of the Excited Charge-Transfer States of Donor−Acceptor Systems

Okamoto, Hiromi; Kinoshita, Mariko

doi:10.1021/jp0126098

Cited by 26 publications

(35 citation statements)

References 29 publications

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“…Recently, Okamoto and Kinoshita published the picosecond infrared spectrum of the ICT state of PP4C in acetonitrile, measured over the frequency range of 920-1700 cm Ϫ1 . 14 Some of the transient bands (1429, ∼290, 1219 and 964 cm Ϫ1 ) are very close in frequency to those observed for the benzonitrile moiety of the ICT state of 4-(dimethylamino)benzonitrile (DMABN), showing that the benzonitrile groups in the ICT state of PP4C and DMABN have a similar structure. It was pointed out that these results can imply that the benzonitrile moiety is decoupled from the electron donor groups (pyrrole or dimethylamino), and that a further discussion on the band assignments and on correlation between structure and spectral pattern is necessary.…”

Section: Introductionsupporting

confidence: 54%

“…It was pointed out that these results can imply that the benzonitrile moiety is decoupled from the electron donor groups (pyrrole or dimethylamino), and that a further discussion on the band assignments and on correlation between structure and spectral pattern is necessary. 14 Information on N- (3-cyanophenyl)pyrrole (PP3C) is limited, only a conference abstract exists in the literature. 15 PP3C has a strongly red-shifted (8000 cm Ϫ1 ) broad fluorescence band in polar solvents as compared with nonpolar media, 15 similar to PP4C.…”

Section: Introductionmentioning

confidence: 99%

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Singlet excited state dipole moments of dual fluorescent N-phenylpyrroles and 4-(dimethylamino)benzonitrile from solvatochromic and thermochromic spectral shifts

Yoshihara

Galievsky

Druzhinin

et al. 2003

Photochem Photobiol Sci

187

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The excited state dipole moments mue(ICT) and mue(LE) of the dual fluorescent molecules N-phenylpyrrole (PP), N-(4-cyanophenyl)pyrrole (PP4C) and N-(3-cyanophenyl)pyrrole (PP3C) are determined from solvatochromic and thermochromic measurements. It is shown that the best results are obtained when the solvatochromic as well as the thermochromic analysis of the spectral shifts is made relative to 4-(dimethylamino)benzonitrile (DMABN) as the model compound. Direct thermochromic experiments with PP4C, PP3C and DMABN in diethyl ether lead to reasonable results, but unrealistically large dipole moments mue(ICT) are found for PP, PP4C, PP3C and DMABN in acetonitrile, ethyl cyanide and n-propyl cyanide. The mue(ICT) values obtained for the N-phenylpyrroles from the thermochromic analysis in these solvents relative to DMABN (17 D) do not depend on solvent polarity: 13 D for PP, 15 D for PP4C and PP3C. The spectral shifts for the LE emission of the N-phenylpyrroles and aminobenzonitriles are much smaller than those for the ICT fluorescence, resulting in relatively small values for mue(LE). With PP and N-(4-methylphenyl)pyrrole (PP4M) the problem arises that one of the two values calculated by solving the quadratic equation for mue(LE) in the solvatochromic and thermochromic analysis cannot be discarded on photophysical or molecular grounds, as is the case for the other molecules. The experimental data for mue(ICT) of PP and PP4C are compared with theoretical values calculated for coplanar (PICT) and perpendicular (TICT) conformations of the pyrrole and phenyl or cyanophenyl groups. The experimental ICT dipole moment of PP4C has a value in between the theoretical results for mue(PICT) and mue(TICT), whereas the data for PP tend to favour the TICT configuration. It appears that in the LE state of PP and PP4M a negative charge remains on the pyrrole moiety, whereas a charge reversal takes place for the LE state of PP3C and the ICT state of PP, PP4C and PP3C.

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Section: Introductionsupporting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Singlet excited state dipole moments of dual fluorescent N-phenylpyrroles and 4-(dimethylamino)benzonitrile from solvatochromic and thermochromic spectral shifts

Yoshihara

Galievsky

Druzhinin

et al. 2003

Photochem Photobiol Sci

187

View full text Add to dashboard Cite

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“…Bond length changes have been estimated experimentally by comparing the vibrational frequencies in the CT state to those in the ground state. Numerous efforts were made to measure the vibrational frequencies of DMABN in the CT state by picosecond IR, 15 , 16 picosecond time-resolved resonance Raman spectroscopies 46 and femtosecond stimulated Raman spectra. 75 The elongation of the C–N amino and C–N cyano bonds in the CT state was confirmed by these experimental studies, supporting the TICT structure in which the π-conjugation including the C–N amino bond is broken.…”

Section: Resultsmentioning

confidence: 99%

Intramolecular Charge-Transfer Excited-State Processes in 4-(N,N-Dimethylamino)benzonitrile: The Role of Twisting and the πσ* State

et al. 2015

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The structural processes leading to dual fluorescence of 4-(dimethylamino)benzonitrile in the gas phase and in acetonitrile solvent were investigated using a combination of multireference configuration interaction (MRCI) and the second-order algebraic diagrammatic construction (ADC(2)) methods. Solvent effects were included on the basis of the conductor-like screening model. The MRCI method was used for computing the nonadiabatic interaction between the two lowest excited ππ* states (S2(La, CT) and S1(Lb, LE)) and the corresponding minimum on the crossing seam (MXS) whereas the ADC(2) calculations were dedicated to assessing the role of the πσ* state. The MXS structure was found to have a twisting angle of ∼50°. The branching space does not contain the twisting motion of the dimethylamino group and thus is not directly involved in the deactivation process from S2 to S1. Polar solvent effects are not found to have a significant influence on this situation. Applying Cs symmetry restrictions, the ADC(2) calculations show that CCN bending leads to a strong stabilization and to significant charge transfer (CT). Nevertheless, this structure is not a minimum but converts to the local excitation (LE) structure on releasing the symmetry constraint. These findings suggest that the main role in the dynamics is played by the nonadiabatic interaction of the LE and CT states and that the main source for the dual fluorescence is the twisted internal charge-transfer state in addition to the LE state.

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“…Only when anti-CEA and anti-AFP are successfully modified on the substrate, it could produce the peaks of C = O, N-H and C-N in FT-IR spectrum simultaneously. As shown in Figure 5, the peak at 1645 cm -1 belonged to C = O stretching vibrations of amide I [43], the peak at 1546 cm -1 belonged to N-H stretching vibrations of amide II [44,45], the peak at 1219 cm -1 belonged to C-N stretching vibrations [46]. It was obvious that amide bonds were formed, which meant that the antibodies were modified on ordered gold nanohoneycomb arrays with success.…”

Section: Characterization Of the Sers Tagsmentioning

confidence: 99%

Multiplexing Determination of Cancer-Associated Biomarkers by Surface-Enhanced Raman Scattering Using Ordered Gold Nanohoneycomb Arrays

Liu

Cao

et al. 2017

Bioanalysis

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Aim:Here, a multiplex surface-enhanced Raman scattering (SERS) based assay for simultaneous quantitation of carcinoembryonic antigen (CEA) and α-fetoprotein (AFP) was developed. Methods: SERS tags of nanostars and SERS substrates of nanobowl arrays were functionalized with labeling and capturing antibodies, respectively. In presence of antigens, SERS tags, antigens and SERS substrates formed sandwich structure. Results: The SERS-based technique showed a wide linear range from 0.5 to 100 ng/ml and detection limits were 0.41 and 0.35 ng/ml for CEA and AFP in phosphate-buffered saline buffer, respectively. Analysis results of clinical serum samples using this technique were similar to that shown in phosphatebuffered saline buffer. The LODs were 0.44 and 0.40 ng/ml for CEA and AFP, respectively. Conclusion: The precision and stability of this analysis technique were satisfactory, meanwhile, no obvious cross-reactivity could be found. What's more, it also suggested that this novel multiplex SERS-based technique could be a simple, specific, reliable, sensitive and multiplexed tool for important diagnostic and prognostic applications. Cancer is a latent fatal illness which kills millions of people worldwide, and the number of people dying from cancer continues to rise. If they were detected and cured earlier, many patients who are dying from cancer would have been saved [1,2]. In clinical diagnosis of cancer, detecting tumor biomarkers at the early stage enables early diagnosis of cancer and receives great deal of attentions [3,4]. Among various cancer biomarker detections, quantified detection of serum biomarkers plays a critical role not only in detecting disease at the early stage, but also in tracking disease development after medical treatment [5]. Recently, varieties of immunoassays and immunosensors are devoted to the detection of a single cancer biomarker [6][7][8]. Although they achieved low detection limits, a majority of cancers have more than one biomarker that correlated with their incidence, and some cancer biomarkers are nonspecific to a special cancer, such as α-fetoprotein (AFP) and carcinoembryonic antigen (CEA), CEA and AFP are related to many kinds of cancer, including liver cancer, colorectal cancer, lung cancer, ovarian carcinoma, breast cancer and pancreatic cancer. Moreover, due to biological diversity of man, only one biomarker detection may generate false positive, which is unreliable [9,10]. Therefore, the detection of a single cancer biomarker is inadequate in diagnosing a special cancer. Comparing with the single biomarker test, multiplex immunoassays of cancer biomarkers can promote the screening and diagnosis of some cancer-related illness [11][12][13]. In addition, the simultaneous multiplex assay that detected more than one cancer biomarker in a single experiment possesses remarkable superiorities, such as shorter analytical time, enhanced detecting throughput, higher efficiency, lower detection cost and less sample. Therefore, it would be advantageous to explore an efficient and ultras...

show abstract

Picosecond Infrared Spectrum of 4-(Pyrrol-1-yl)benzonitrile: Structure of the Excited Charge-Transfer States of Donor−Acceptor Systems

Cited by 26 publications

References 29 publications

Singlet excited state dipole moments of dual fluorescent N-phenylpyrroles and 4-(dimethylamino)benzonitrile from solvatochromic and thermochromic spectral shifts

Singlet excited state dipole moments of dual fluorescent N-phenylpyrroles and 4-(dimethylamino)benzonitrile from solvatochromic and thermochromic spectral shifts

Intramolecular Charge-Transfer Excited-State Processes in 4-(N,N-Dimethylamino)benzonitrile: The Role of Twisting and the πσ* State

Multiplexing Determination of Cancer-Associated Biomarkers by Surface-Enhanced Raman Scattering Using Ordered Gold Nanohoneycomb Arrays

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