1. Dispersed Fluorescence Spectroscopy of Jet-Cooled p-Aminotoluene 61 st OSU ISMS 2006 Partha Biswas, a) Montu Kumar Hazra a) and Tapas Chakraborty a,b) a) Department of Chemistry, Indian Institute of Technology Kanpur, UP 208016, india b) Department of Physical Chemistry, Indian association for the Cultivation of Science, Jadavpur, Calcutta 700032, india

2. Yan, S.; Spangler, L. H. J. Chem. Phys. 1992, 96, 4106. p-Aminotoluene Methyl –internal rotation Amine –umbrella-type inversion and torsional motion. Yan, S.; Spangler, L. H. J. Chem. Phys. 1992, 96, 4106 Tan, X. Q.; Pratt, D. W. J. Chem. Phys. 1994, 100, 7061 How these two moieties interact with each other through the aromatic ring and what is the consequence of that? p-Aminotoluene is an ideal system to investigate the ring-mediated coupling between the large- amplitude motions associated with methyl and amine

3. Fluorescence excitation spectra of a.p-Fluorotoluene b.p-Fluoroaniline and c.p-Aminotoluene Ju, Q..; Parmenter, C.S..; Stone, T.A.; Zhao, Z-Q. Israel J. Chem. 1997, 37, 379. d-substitution

4. Dispersed Fluorescence spectra exciting the origin bands of a.p-Fluorotoluene b.p-Fluoroaniline and c.p-Aminotoluene Ju, Q..; Parmenter, C.S..; Stone, T.A.; Zhao, Z-Q. Israel J. Chem. 1997, 37, 379.

5. Comparison of Dispersed Fluorescence spectra exciting the 6a mode of p-Aminotoluene and p-Fluoroaniline 6a

6. Comparison of Dispersed Fluorescence spectra exciting the 711 and 730 cm -1 band of p-aminotoluene and p-fluoroaniline respectively

7. Comparison of Dispersed Fluorescence spectra exciting the Inversion mode of p-Aminotoluene and p-Fluoroaniline 6a

8. Theoretical prediction is indicating the amino torsion (mode 44) mixed with out-of-plane mode 39 and mode 41 and in-plane mode 42 upon electronic excitation but not with mode 45 (methyl torsion) of p-Aminotoluene Q' 39 =-0.949Q" 38 + 0.285Q" 39 + 0.120Q" 40 Q' 40 =-0.275Q" 38 -0.942Q" 39 - 0.177Q" 44 Q' 41 =-0.109Q" 40 + 0.634Q" 41 - 0.760Q" 42 Q' 42 = 0.996Q" 43 Q' 43 = 0.165Q" 39 + 0.161Q" 41 + 0.128Q" 42 - 0.960Q" 44 Q' 44 =-0.747Q" 41 - 0.630Q" 42 - 0.179Q" 44 Q' 45 =-0.996Q" 45 Mode-39 Frequency-527 cm -1 16b Mode-41 Frequency-436 cm -1 16a Mode-42 Frequency-430 cm -1 9b Normal modes in the S 0 state those are mixed with amino torsion mode-44 S 1 modes Expansion in S 0 modes Limitation of the calculation in harmonic limit !!! (ab initio calculations are performed in CASSCF(8,7)/6-311g** level)

9. Dispersed Fluorescence spectral signatures of excited state IVR

10. Interact with each other via aromatic ring p-vinyltoluene Biswas, P.; Panja, S. S.; Manogaran, S.; Chakraborty, T. J. Phys. Chem. A 2005, 109, 3225.

11. Fluorescence excitation spectra of a. p-vinylfluorobenzene b. toluene and c. p- vinyltoluene, Hickman, C.G.; Gascooke, J.R. ; Lawrence, W.D. J. Chem. Phys. 1996, 104, 4887.

12. Dispersed fluorescence spectra following excitations of the origin band, 214 & 235 cm -1 vibronic bands of the fluorescence excitation spectrum of p-vinyltoluene Mode 49 – vinyl bending ;Mode 50 – vinyl torsion ;Mode 51-methyl torsion

13. * Appearance of these bands are indicative of partial mixing of in-plane and out of plane modes involving the methyl torsional mode upon electronic excitation Dispersed fluorescence spectra following excitations of the 335, 417, 450 and 507 cm -1 vibronic bands of the fluorescence excitation spectrum of p-vinyltoluene

14. Theoretical prediction is indicating the Duschinsky mixing of methyl torsion (mode 51) with vinyl torsion (mode 50) and out-of-plane vinyl bending (mode 49) modes upon electronic excitation of p-vinyltoluene Q 47 ’ = 0.139 Q 46 ’’ - 0.960 Q 47 ’’ - 0.161 Q 48 ’’ Q 48 ’ = -0.129 Q 46 ’’ - 0.215 Q 47 ’’ + 0.944 Q 48 ’’ - 0.139 Q 50 ’’ Q 49 ’ = -0.111 Q 47 ’’ - 0.204 Q 48 ’’ - 0.760 Q 49 ’’ - 0.562 Q 50 ’’ - 0.213 Q 51 ’’ Q 50 ’ = -0.610 Q 49 ’’ + 0.732 Q 50 ’’ + 0.282 Q 51 ’’ Q 51 ’ = 0.360 Q 50 ’’ - 0.932 Q 51 ’’ S 1 modes Expansion in S 0 modes Mode-50 Frequency-12 cm -1 Mode-49 Frequency-141 cm -1 Mode-48 Frequency-305 cm -1 Mode-47 Frequency- 431 cm -1 Mode-46 Frequency- 486 cm -1 Mode-51 Frequency- 15 cm -1 Normal modes in the ground electronic state (ab initio calculations are performed in CASSCF(8,8)/6-31g** level)

15. In p-Aminotoluene……. The features of our measured dispersed fluorescence spectra presented here bear signatures of coupling of amine inversion and torsion with low- energy modes involving the methyl group. Specifically, the dispersed fluorescence spectrum measured following excitation of a vibronic band of 711 cm -1 excess energy reveal coupling of amine torsion with the mode corresponds to methyl motion of out-of-plane bending type. Furthermore, dispersed fluorescence spectral features for excitation with 737 cm -1 excess energy shows that amine inversion motion is coupled with ring vibration of 16a type with methyl torsion as well as out-of-plane methyl bending vibration. The details of the analysis will be published elsewhere. Summary and Conclusion:

16.  Labmates: Chayan K. Nandi, Sujit S. Panja, V. Ramanathan, Amit Samanta, Prasenjit Pandey, Biman Bandopadhay  Prof. S. Manogaran,IIT Kanpur, India  Indian Institute of Technology Kanpur, INDIA  Department of Science and Technology, Govt. of India. Acknowledgement