2009-04-09 JMFrost - Fullerene Talk to Chemistry

An early version of the data on PCBM adducts (just Bis I think at this stage?). This was put together very quickly, for a talk over in Chemistry.

The results that followed from this were the key ones of my PhD.

To form the SMILES strings for PCBM with arbitrary attachment points, I borrowed a PhD friend's indoor Football (which is the same shape) and used post-it notes to locate the sidechains, while I rotated in in front of my eyes + checked that it agreed with the hand-annotated Schlegel diagrams in my lab book that I had built for each adduct.

I had evidently already started a combinatory sift, and found the CPDT fullerene, though hadn't yet managed to calculate Tris adducts.

Transcript

1. HOMO/LUMO of Fullerene Adducts A Quantum Chemical Study Jarvist Frost, James Kirkpatrick, Jenny Nelson Physics Department, Imperial College London
2. Schlegel Diagram
3. SMILES (Simplified molecular input line entry specification) (C1%61%98C2%99C3C4C5C61C7C8C9%61C%10C%11C%122C%13C%143C%15C%16C%174C %18%96C%195C%20C%217C%22C%23C%248C%25C%26%10C%27C%28%11C%29C%30%13C%31C %32%15C%33C%34%16C%35C%36%97%18C%37C%38%20C%39%22C%40C%41C%42%23C %43%25C%44C%45%27C%46C%47%29C%48%31C%49C%50%33C%51C%52%35C%53%37C %54%40C%55C%56%51C%57%49C%58%46C%59%44C%60%41%55) [C1 Isomer] (c1(h)c(h)c(h)c(h)c(h)c1C%X%Y(C(h)(h)C(h)(h)C(h)(h)C(O)OC(h)(h)(h))) [PBM Tail] (c1(h)c(h)c(h)c(h)c(h)c1C%98%99(C(h) (h)C(h)(h)C(h)(h)C(O)OC(h)(h)(h)))(hC %96%97(h)) (C1%61%98C2%99C3C4C5%96C6%971 C7C8C9%61C%10C%11C%122C%13C %143C%15C%16C%174C%18C%195C %20C%217C%22C%23C%248C%25C %26%10C%27C%28%11C%29C %30%13C%31C%32%15C%33C %34%16C%35C%36%18C%37C %38%20C%39%22C%40C%41C %42%23C%43%25C%44C%45%27C %46C%47%29C%48%31C%49C %50%33C%51C%52%35C%53%37C %54%40C%55C%56%51C%57%49C %58%46C%59%44C%60%41%55) (smi23d) (UFF, AM1, DFT) HOMO: Highest Occupied KS Energy Level (well defined) HOMO+1: First virt KS orbital (badly defined, but free) E(Anion)-E(Neutral): Further SCF calculation of charged molecule without nuclear coordinated relaxation HOMO+TD-DFT(1st Singlet): TD-DFT 'spectroscopic' calculation L U M O {
7. Bis-Cyclopentadithiophene-PBM HOMO LUMO (eV) C1: -5.22893 -3.46713 C2: -5.30618 -3.34498 C3: -5.30590 -3.4574 E': -5.28632 -3.34532 T1: -5.27054 -3.44314 T2: -5.29720 -3.4211 T3: -5.37526 -3.47596 T4: -5.32576 -3.43576 Mono-PCBM: -3.74881 Lifted HOMO (effect on working cell?) Lifted LUMO (~300meV c.f. Mono-pcbm) Homo spin density on Thiophene unit Thiophene unit fairly compact (effect on packing) Further Work: Different adducts, higher order adducts Understanding effect of varying Lumo of isomers on performance (fill factor?) Combine with simplistic MD to generate amorphous films + charge transport studies
8. Comparison of DFT Methods for Molecular Orbital Eigenvalue Calculations – Gang Zhang et al. J. Phys. Chem. A 2007, 111, 1554-1561 Principles of Fullerene Reactivity – Andreas Hirsch. Topics in Current Chemistry, Vol. 199 Fullerene Chemistry in Three Dimensions – Andreas Hirsch et al. Angew. Chem. Int. Ed. Engl. 1994, 33, No. 4 The Addition Patterns of C60 Trisadducts – Francis Djojo et al. Eur. J. Org. Chem. 1999, 3027-3039 Lecture Notes on Fullerene Chemistry – Roger Taylor, Imperial College Press 1999 Pi-Conjugated Fullerene Adducts – Floris Berend Kooistra, PhD Thesis 2007, University of Groningen Acknowledgments and References Jenny Nelson (Supervisor) James Kirkpatrick (Gaussian Assistance + awk scripts) Kevin Gilbert, Rajarshi Guha - Indiana University (smi23d coordinate generation) Other Software: Openbabel, Gaussian 03, PyMol High Performance Computing facility, Imperial College London (2.5 CPU-Years)