Some applications related to Chapter 11 material: We will see how the kind of basic science we discussed in Chapter 11 will probably lead to good advances in applied areas such as: 1- Design of efficient solar cell dyes based on charge transfer absorption. 2- Strongly luminescent materials based on the Jahn-Teller effect.

1- Design of efficient solar cell dyes based on charge transfer absorption

These complexes should have charge transfer from metal or ligand orbitals to the  * orbitals. diimine dithiolate

CT-band for Pt(dbbpy)tdt Data from: Cummings, S. D.; Eisenberg, R. J. Am. Chem. Soc. 1996,

X- Chloride Connick W. B.; Fleeman, W. L. Comments on Inorganic Chemistry, 2002, 23, X-thiolate  * bpy d x2-y2 d xz-yz d xy d xz+-yz d z2  bpy {  (thiolate) + d  (Pt) CT to diimine hv

Electronic absorption spectra for dichloromethane solutions of (dbbpy)Pt(dmid), 1, (thin line) and [(dbbpy)Pt(dmid)] 2 [TCNQ], 3, (thick line) in the UV/VIS region (left) and NIR region (right). Smucker, B; Hudson, J. M.; Omary, M. A.; Dunbar, K.; Inorg. Chem. 2003, 42,

hv HOMO LUMO Clearly a d x2-y2 orbital, not a diimine  * By Brian Prascher, Chem 4610 student, 2003

MO diagram for the M(diimine)(dithiolates) class!!! So the lowest-energy NIR bands are d-d transitions and the LUMO is indeed d x2-y2, not diimine  *  * bpy d x2-y2 d xz-yz d xy d xz+-yz d z2  bpy {  (thiolate) + d  (Pt)  * bpy d x2-y2 {  (thiolate) + d  (Pt)

WHO CARES!! The above was science, let’s now see a potential application

Silicon cells –10-20 % efficiency –Corrosion –Expensive (superior crystallinity required) Wide band gap semiconductors (e.g. TiO 2 ; SnO 2 ; CdS; ZnO; GaP): –Band gap >> 1 eV (peak of solar radiation) –Solution: tether a dye (absorbs strongly across the vis into the IR) on the semiconductor –Cheaper!!… used as colloidal particles

Literature studies to date focused almost solely on dyes of Ru(bpy) 3 2+ derivatives ==> Strong absorption across the vis region (Grätzel; Kamat; T. Meyer; G. Meyer; others)

ArS - group Y= Cl -, BF 4 -, TCNQ - [M(N 3 )(X)] + Y - where M = Pt(II), Pd(II) or Ni(II); N3=triimine; X = anionic ligand (SCN -, halide, RS -, etc.).

Absorption Spectra of [Pt(tbtrpy)X] + Y - Complexes Using ArS - ligands as X shifts the CT absorption to the VIS region. Using TCNQ - as Y adds NIR absorptions.

2- Strongly luminescent materials based on the Jahn-Teller effect

Forward, J.; Assefa, Z.; Fackler, J. P. J. Am. Chem. Soc. 1995, 117, McCleskey, T. M.; Gray, H. B. Inorg. Chem. 1992, 31, Ground-state MO diagram of [Au(PR 3 ) 3 ] + species, according to the literature: [Au] + (5d 10 ) [Au(PR 3 ) 3 ] + PR

Molecular orbital diagrams (top) and optimized structures (bottom) for the 1 A 1 ’ ground state (left) of the [Au(PH 3 ) 3 ] + and its corresponding exciton (right). Barakat, K. A.; Cundari, T. R.; Omary, M. A. J. Am. Chem. Soc. 2003, 125, By Khaldoon Barakat, Chem 5560 student, 2002

[Au(TPA) 3 ] + QM/MM optimized structures of triplet [Au(PR 3 ) 3 ] + models. em = 478 nm em = 772 nm em = 640 nm em = 496 nm Barakat, K. A.; Cundari, T. R.; Omary, M. A. J. Am. Chem. Soc. 2003, 125,

WHO CARES!! The above was science, let’s now see a potential application

RGB bright emissions in the solid state and at RT are required for a multi-color device….

AuL 3 as LED materials? Glow strongly in the solid state at RT. But [Au(PR 3 ) 3 ] + X - don’t sublime into thin films (ionic). How about neutral Au(PR 3 ) 2 X?: –Do they also luminesce in the solid state at RT? –Do they also exhibit distortion to a T-shape?

T-shape and BEYOND! “Photocrystallography” and time-resolved EXAFS should tell us if these distortions toward and beyond a T-shape will really take place experimentally…stay tuned! Au(PPh 3 ) 2 Cl. Bond angles shown are: B3LYP; HF (exptl.).

* The lifetime (7.9  s) suggests that the emission is phosphorescence from a formally triplet excited state.