Problem to Be Solved: to provide a chromophore having a far superior nonlinear optical activity to conventional chromophores and to provide a nonlinear optical element comprising said chromophore. Solution: a chromophore comprising a donor structure D, a -conjugated bridge structure B, and an acceptor structure A, the donor structure D comprising an aryl group substituted with a substituted oxy group; and a nonlinear optical element comprising said chromophore.

Nonlinear optical chromophores having one or more diamondoid groups covalently attached to the chromophore, methods of making nonlinear optical chromophores, their use in thin films and electro-optical devices containing such nonlinear optical chromophores and thin films comprising the same.

A nonlinear optical dye includes a compound represented by the general formula (1) below. ##STR00001## In the above general formula (1), each of X.sup.1, X.sup.2, X.sup.3 and X.sup.4 independently represents a hydrogen atom, an alkyl group having a carbon number of 1 to 6, a halogen atom, a hydroxyl group, a nitro group, a cyano group, or a methylsulfonyl group. In the present invention, it is preferred that each of X.sup.1, X.sup.2, X.sup.3 and X.sup.4 independently represents a hydrogen atom, an alkyl group having a carbon number of 1 to 6, or a halogen atom. In the present invention, it is also preferred that the nonlinear optical dye has a dipole moment of 2.1 D or less and a maximum absorption wavelength within a range of 315 to 360 nm.

A compound for spacing nonlinear optical chromophores of the Formula I

##STR00001##

and the commercially acceptable salts, solvates and hydrates thereof, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, W, X, Y, Z, Q.sup.1, Q.sup.2, Q.sup.4 and L have the definitions provided herein.

Hydrogels that degrade under appropriate conditions of pH and temperature by virtue of crosslinking compounds that cleave through an elimination reaction are described. The hydrogels may be used for delivery of various agents, such as pharmaceuticals.

A compound for spacing nonlinear optical chromophores of the Formula I

##STR00001##

and the commercially acceptable salts, solvates and hydrates thereof, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, W, X, Y, Z, Q.sup.1, Q.sup.2, Q.sup.4 and L have the definitions provided herein.

Nonlinear optical chromophore compositions which display lyotropic nematic liquid crystal phases in polar organic solvents and provide a mechanical anisotropic effect allowing for the formation of a non-centrosymmetric chromophore-polymer matrix without the application of an electric field.

##STR00001##

Nonlinear optical chromophores having one or more diamondoid groups covalently attached to the chromophore, methods of making nonlinear optical chromophores, their use in thin films and electro-optical devices containing such nonlinear optical chromophores and thin films comprising the same.

Hydrogels that degrade under appropriate conditions of pH and temperature by virtue of crosslinking compounds that cleave through an elimination reaction are described. The hydrogels may be used for delivery of various agents, such as pharmaceuticals. This invention provides hydrogels that degrade to smaller, soluble components in a non-enzymatic process upon exposure to physiological conditions and to methods to prepare them. The hydrogels are prepared from crosslinking agents that undergo elimination reactions under physiological conditions, thus cleaving the crosslinking agent from the backbone of the hydrogel. The invention also relates to the crosslinking agents themselves and intermediates in forming the hydro gels of the invention. The biodegradable hydro gels prepared according to the methods of the invention may be of use in diverse fields, including biomedical engineering, absorbent materials, and as carriers for drug delivery.

Nonlinear optical chromophores having one or more diamondoid groups covalently attached to the chromophore, methods of making nonlinear optical chromophores, their use in thin films and electro-optical devices containing such nonlinear optical chromophores and thin films comprising the same.