Tobin Marks and Mark RatnerNorthwestern University

DMR-0353831Twisted π-Electron “Super Chromophores” for Electro-Optics

Worldwide progress in the development ofchromophores having exceptionally large molecular hyperpolarizabilities.

Electro-optic materials based on molecular π-electron chromophores offer the exciting promise of enabling ultra-highspeed optical data transmission and processing.A joint theoretical + synthetic effort by Mark Ratner and Tobin Marks at Northwestern University, in collaboration with researchers at the University of Milano and the University of Perugia in Italy, and the University of Leuven in Belgium, has demonstrated a new concept for chromophore design in which the key materials parameter, , the molecular hyperpolarizability, is maximized by twisting from planarity a π-electron system connecting donor and acceptor substituents. In the accompanying figure, the hyperpolarizability multiplied by the dipole moment () is the quantity measured and is normalized for the molecular weight of the chromophore, Mw. The largest response measured for a twisted chromophore ( = -488,000 x 10-48 esu) is ca. 20x grater than that of any previously reported molecular chromophore.

1985 1990 1995 2000 2005

0

200

400

600

800

1000

NO

t-Bu

t-Bu

N CN

CN

N

t-BuMe2SiO

t-BuMe2SiOO

CN CN

CN

NBu

Bu S

NCCN

CN

NN

Me2NNO2

Tobin Marks and Mark RatnerNorthwestern University

DMR-0353831 Twisted π-Electron “Super Chromophores” for Electro-Optics

Worldwide progress in the development ofchromophores having exceptionally large Molecular hyperpolarizabilities.

1985 1990 1995 2000 2005

0

200

400

600

800

1000

NO

t-Bu

t-Bu

Northwestern5702005

Northwestern943.32005

Northwestern57.82005

NCN

CN

N CN

CN

45.72000

N

t-BuMe2SiO

t-BuMe2SiOO

CN CN

CN

27.11996

NBu

Bu

SO

O

NC

CN

25.51993 2.1

1987

NBu

Bu S

NCCN

CN

NN

Me2NNO2

/M

w a

t 19

07 n

m (

10-4

8es

u)

Year

Broader Impact of this ResearchDMR-0353831

Technological and Commercial Applications

contacts underway with four major corporations interested in high-speed communications hardware

International Collaborations

This is joint work with Leuven (Belgium), Milano ( Italy), and Perugia (Italy).

In a joint project with Cork (Ireland), we are investigation the generality of this twist-controlled hyperpolarizability enhancement