Luminescence Depolarization Dynamics of Quantum Dots:  Is It Hydrodynamic Rotation or Exciton Migration?

Narayanan, Shankar; Sarkar, Rupa; Sinha, Sudarson Sekhar; Dias, Fernando B.; Monkman, and Andy; Pal, Samir Kumar

doi:10.1021/jp710354z

Cited by 9 publications

(9 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This restricted rotation of PF has been used to calculate the microviscosity of the protein cavity according to the Stokes-Einstein-Debye equation. 26 The microviscosity at the active site of the protein is thus estimated to be 5 cP at 10 °C. The corresponding viscosity of buffer at the same temperature is 1.3 cP.…”

Section: Resultsmentioning

confidence: 99%

Conformational Dynamics at the Active Site of α-Chymotrypsin and Enzymatic Activity

Banerjee

Pal

2008

Langmuir

Self Cite

View full text Add to dashboard Cite

The role of dynamical flexibility at the active site of a proteolytic enzyme alpha-chymotrypsin (CHT) has been correlated with its catalytic activity. The temperature-dependent efficiency of catalysis reveals a bell-shaped feature with a peak at 37 degrees C, the typical body temperature of homeothermal animals. The overall structural integrity of the enzyme in our experimental temperature range has been confirmed from dynamic light scattering (DLS) and circular dichroism (CD) studies. We have followed the dynamical evolution at the active site of CHT with temperature using picosecond-resolved fluorescence anisotropy of anthraniloyl probe (covalently attached to the serine-195 residue) and a substrate mimic (inhibitor) proflavin. The conformational dynamics at the active site is found to have a distinct connection with the enzyme functionality. The conformational flexibility of the enzyme is also evidenced from the compressibility studies on the enzyme. The site selective fluorescence detected circular dichroism (FDCD) studies reveal that the conformational flexibility of the enzyme has an effect on the structural perturbation at the active site. We have also proposed the possible implications of the dynamics in the associated energetics.

show abstract

Section: Resultsmentioning

confidence: 99%

Conformational Dynamics at the Active Site of α-Chymotrypsin and Enzymatic Activity

Banerjee

Pal

2008

Langmuir

Self Cite

View full text Add to dashboard Cite

show abstract

“…Time-resolved fluorescence decays were recorded using the time-correlated single photon counting (TCSPC) method. [72][73][74][75][76] Data analysis was carried via commercial software provided by Horiba Instruments.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

“…Steady-state fluorescence and time-resolved fluorescence decays were determined on a Horiba Jobin Yvon FluoroMax-4 spectrofluorometer. Time-resolved fluorescence decays were recorded using the time-correlated single photon counting (TCSPC) method. − Data analysis was carried via commercial software provided by Horiba Instruments.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

The Effect of Intermolecular Hydrogen Bonding on the Fluorescence of a Bimetallic Platinum Complex

et al. 2010

View full text Add to dashboard Cite

The bimetallic platinum complexes are known as unique building blocks and arewidely utilized in the coordination-driven self-assembly of functionalized supramolecular metallacycles. Hence, photophysical study of the bimetallic platinum complexes will be very helpful for the understanding on the optical properties and further applications of coordination-driven self-assembled supramolecular metallacycles. Herein, we report steady-state and time-resolved spectroscopic experiments as well as quantum chemistry calculations to investigate the significant intermolecular hydrogen bonding effects on the intramolecular charge transfer (ICT) fluorescence of a bimetallic platinum compound 4,4'-bis(trans-Pt(PEt(3))(2)OTf)benzophenone 3 in solution. We demonstrated that the fluorescent state of compound 3 can be assigned as a metal-to-ligand charge transfer (MLCT) state. Moreover, it was observed that the formation of intermolecular hydrogen bonds can effectively lengthen the fluorescence lifetime of 3 in alcoholic solvents compared with that in hexane solvent. At the same time, the electronically excited states of 3 in solution are definitely changed by intermolecular hydrogen bonding interactions. As a consequence, we propose a new fluorescence modulation mechanism by hydrogen bonding to explain different fluorescence emissions of 3 in hydrogen-bonding solvents and nonhydrogen-bonding solvents.

show abstract

“…Steady-state fluorescence and time-resolved fluorescence decays were determined on a HORIBA JOBIN YVON FluoroMax-4 spectrofluorometer. Time-resolved fluorescence decays were recorded using the time-correlated single photon counting (TCSPC) method. – Data analysis was carried out on commercial software provided by Horiba Instruments. The quality of the fits was measured by the χ 2 values and distribution of residuals.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

“…Time-resolved fluorescence decays were recorded using the time-correlated single photon counting (TCSPC) method. [36][37][38][39][40][41] Data analysis was carried out on commercial software provided by Horiba Instruments. The quality of the fits was measured by the χ 2 values and distribution of residuals.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Photophysical Properties of Coordination-Driven Self-Assembled Metallosupramolecular Rhomboids: Experimental and Theoretical Investigations

et al. 2010

View full text Add to dashboard Cite

In this work, the photophysical properties of coordination-driven self-assembled metallosupramolecular rhomboids with the donor ligands 1,2-bis(3-pyridyl)ethyne (3a) and 1,4-bis(3-pyridyl)-1,3-butadiyne (3b) are investigated by use of both spectroscopic experiments and quantum chemistry calculations. All the geometric conformations of the chair and boat conformers of 3a and 3b are fully optimized using density functional theory. The time-dependent density functional theory method was also used to study the excited-state properties of these self-assembled metallosupramolecular rhomboids. At the same time, steady-state absorption and fluorescence as well as the time-correlated single photon counting techniques are used to measure their various spectral properties. The fluorescence spectra of these self-assembled metallosupramolecular rhomboids are very wide and show an evident two-peak feature, which can be tuned by different excitation wavelengths. It has been demonstrated that the chair conformers of both 3a and 3b are formed preferentially over their boat conformers due to the close proximity of the chelated bisphosphine platinum groups. Moreover, an additional shoulder observed at 416 nm in the fluorescence spectra of 3b indicates the presence of minor amounts of the boat conformer of 3b. In addition, we have also demonstrated that lengthening the acetylene chain of the donor ligand component of these rhomboids results in a red-shifted and broadened absorption band for these metallosupramolecular rhomboids. Furthermore, the nature of the excited states for these metallosupramolecular rhomboids varies with the acetylene chain length of the donor ligands and with the different conformers.

show abstract

Luminescence Depolarization Dynamics of Quantum Dots: Is It Hydrodynamic Rotation or Exciton Migration?

Cited by 9 publications

References 33 publications

Conformational Dynamics at the Active Site of α-Chymotrypsin and Enzymatic Activity

Conformational Dynamics at the Active Site of α-Chymotrypsin and Enzymatic Activity

The Effect of Intermolecular Hydrogen Bonding on the Fluorescence of a Bimetallic Platinum Complex

Photophysical Properties of Coordination-Driven Self-Assembled Metallosupramolecular Rhomboids: Experimental and Theoretical Investigations

Contact Info

Product

Resources

About