Dr. Parantap Sarkar conducted postdoctoral research at 3 institutions over 7 years. His research included: 1) Synthesis of N-heterocyclic carbene adducts in India and South Korea. 2) Synthesis of flexible and rigid nanohoops in Japan, including the first belt-shaped cyclonaphthylenes. 3) Synthesis of a cyclophenanthrenylene nanohoop with heterogeneous biaryl linkages in Japan, which exhibited unique cyclostereoisomerism and restricted rotation at ambient temperature.

1. Presentation of Post Doctoral Research
Dr. Parantap Sarkar
Postdoctoral Experience
1. IISER Kolkata, India (Oct 2012 – Jan 2013, 4 months)
2. Ewha Womans University, South Korea (March 2013 – Feb 2014, 1 year)
3. WPI-AIMR, Tohoku University, Japan (Apr 2014 – Jan 2017, 2 years 10 months)

2. 1. IISER Kolkata, India
Work on progress
synthesis that was finished by me in 4 months
Yield of the steps were not optimized
due to lack of time

3. 2. Ewha Womans University, South Korea
Project A. Synthesis of NHC-fullerene adduct

4. Project B. Synthesis of NHC-bis Carbene
2. Ewha Womans University, South Korea
NN
N
PhPh
Dipp
NN
N
PhPh
Ar
SS
MeMe
2 OTf -
(writing in progress)
synthesis of N-heterocyclic bis-carbene
NN
Ph
Ph NN
N
PhPh
Ar
SS
MeOTf/ CH2Cl2
r.t. 3 d
75%
NN
N
PhPh
Ar
NHHN
PhPh Ph-NCS
nBuLi, CS2
60%
LiAlH4
90%
N2H4/ EtOH
Pd-C, r.t.
100%

5. 1991
Flexible
nanohoops
Rigid
nanohoops
3. WPI-AIMR Tohoku University, Japan
Project A & B: Introduction
Project A Project B

6. 3. WPI-AIMR Tohoku University, Japan
Project A
Unbridged (flexible at r.t. in solution)
Angew. Chem. 2015, 54, 12800-12804

7. 3. WPI-AIMR Tohoku University, Japan
Project A
Angew. Chem. 2015, 54, 12800-12804

8. 3. WPI-AIMR Tohoku University, Japan
Project A
!b-[8]CaNAP
OO
Cu(OTf)2
DCE
pinB-Bpin
[Ir(cod)OMe]2
dtbpy
pinB Bpin
i) PtCl2(cod), CsF
THF, 70 °C
ii) PPh3, o-DCB
180 °C
Angew. Chem. 2015, 54, 12800-12804

9. 3. WPI-AIMR Tohoku University, Japan
Project A
Angew. Chem. 2015, 54, 12800-12804

10. 3. WPI-AIMR Tohoku University, Japan
Project A
Conclusion of Project A
1. the first belt-shaped cyclonaphthylenes were synthesized, and their
structures were revealed by crystallographic and spectroscopic analyses.
2. The rigidity of the nanohoop structures is reinforced by methylene bridges,
which gives rise to the atropisomerism of cyclonaphthylene in solutionand
correlated rotation.

11. 3. WPI-AIMR Tohoku University, Japan
Project B
Chem. Lett. 2015, 44, 1582-1583

12. 3. WPI-AIMR Tohoku University, Japan
Project B
Chem. Lett. 2015, 44, 1582-1583

13. 3. WPI-AIMR Tohoku University, Japan
Project B
Chem. Lett. 2015, 44, 1582-1583

14. Slow arylene rotation
3. WPI-AIMR Tohoku University, Japan
Project B
Chem. Lett. 2015, 44, 1582-1583

15. 3. WPI-AIMR Tohoku University, Japan
Project B
Chem. Lett. 2015, 44, 1582-1583

16. 3. WPI-AIMR Tohoku University, Japan
Project B
Conclusion of Project B
1. Synthesis of a new member in cyclo-arylene chemistry with very high
numbers of π-degenerated system.
2. Investigation on the rotational behavior of the arylene units in the hybrid
nanohoop that revealed both free arylene rotation and correlated rotation.
3. Considering the synchronous broadening of the 1H-NMR resonances, we
believe, that the correlated rotation of anthanthrenylene-phenylene is
occurring competitively with the single phenylene rotation in solution.

17. 3. WPI-AIMR Tohoku University, Japan
Project C
&
H3C
CH3
CH3
CH3
H3C
H3C
CH3
H3C
P M
U-[8]CaNAP
[8]CPhen3,9
Introduction
ACS Cent. Sci. 2016, 2(10), 740-747

18. 3. WPI-AIMR Tohoku University, Japan
Project C
ACS Cent. Sci. 2016, 2(10), 740-747

19. 3. WPI-AIMR Tohoku University, Japan
Project C
H3C
CH3
CH3
CH3
H3C
H3C
CH3
H3C
=
ACS Cent. Sci. 2016, 2(10), 740-747

20. 3. WPI-AIMR Tohoku University, Japan
Project C
Crystal Structure
Condition to obtain
Single crystal:
Slow diffusion of
pentane into o-DCB
solution of
[8]CPhen3,9
3-3’ linkage
9-9’ linkage
Dihedral angles :
4-3-3’-4 linkage => 141°, 149°, 166°, 166°
8a-9-9’-8a’ linkage => –142°, –142°, –143°, –143°
ACS Cent. Sci. 2016, 2(10), 740-747

21. 3. WPI-AIMR Tohoku University, Japan
Project C
Separation of [8]CPhen3,9 enantiomers and CD Spectra
Analytical HPLC Chromatogram
Column: Cosmosil Cholester
(250+250+250) mm x 4.6 ϕ
Eluent: 30% MeOH in CHCl3
CD spectra of isolated
enantiomers in toluene at 25 °C.
(by Prep. HPLC)
Gray bars show the rotatory
velocity calculated by the DFT
method at the B3LYP/6-31G(d,p)
level of theory for the
(E,R,E,R,E,R,E,R)-structure.
ACS Cent. Sci. 2016, 2(10), 740-747

22. 3. WPI-AIMR Tohoku University, Japan
Project C
VT-NMR study
ACS Cent. Sci. 2016, 2(10), 740-747

23. 3. WPI-AIMR Tohoku University, Japan
Project C
Conclusion of Project C
1. Cyclophenanthrenylene nanohoop with heterogeneous biaryl linkage has been
synthesised.
1. Due to presence of R/S-linkage the nanohoop deviates from coplanar belt-
shape and unique cyclostereoisomerism has been emerged.
1. The nanohoop follows two-stage isomerization pathways, E/Z- and R/S-
isomerization respectively, where the later is restricted at ambient temperature
resulting isolable stereoisomers with intrinsic axial chirality at biaryl linkages.