WO1990005722A1 - Phthalimide compounds for forming amorphous layers by vacuum deposition - Google Patents

Abstract

There are disclosed phthalimide compounds of structure (I), wherein R and R1 are independently selected from the group consisting of nitro, foramido groups, carbamoyl groups and heterocyclic groups derived from amino or carboxyl groups.

Description

PHTHALIMIDE COMPOUNDS FOR FORMING AMORPHOUS LAYERS BY VACUUM DEPOSITION Technical Field

The present invention relates to new compounds that are useful in the preparation of layers of transparent materials which provide an optic function. The compounds are phthalimides that can be vacuum deposited to provide the transparent layer. Background Art

Transparent layers for optical devices can serve a variety of optical functions. For example, the optical performance of a lens can be improved by providing an antireflecting coating. Such a coating, for example, can improve the contrast of the lens in a variety of conditions. Such antireflecting coatings are made by depositing a layer or layers of material having predetermined indices of refraction in predetermined thicknesses to achieve the desired antireflective condition.

Processes wherein polymers or monomers are solvent coated on the support, suffer from many disadvantages. First, solution coating, whether it be of the polymer or the monomers, produces layers which are of less than desired uniformity for optical applications. Further, these processes inevitably leave residual solvent in the layer which is disadvantageous for long term storage or subsequent process steps. In addition-, multiple layers are difficult if not impossible since the solvent used to coat the second layer often attacks the first layer or will not wet the surface of the first layer.

It is common to coat inorganic materials using vacuum coating techniques. This type of coating is capable of producing uniform coatings without solvents. Multiple layers are more easily achieved than with solvent coating. However, vacuum coating is not possible with these organic polymeric materials. The organic polymers do not have sufficient vapor pressure to evaporate even under high vacuum conditions. If the temperature of the polymer is raised to increase the vapor pressure, the polymer decomposes.

Thus, the problem to be solved by the present invention is to provide new compounds that can be vacuum coated to provide useful optical layers. Disclosure of the Invention

In accordance with the present invention, there are provided phthalimide compounds of the structure:

wherein R and R are independently selected from the group consisting of nitro, foramido groups, carbamoyl groups and heterocyclic groups derived from amino or carboxyl groups.

The phthalimide compounds of the invention have the structure:

wherein R and R are independently selected from the group consisting of nitro, foramido groups, carbamoyl groups and heterocyclic groups derived from amino or carboxyl groups.

The parent amino and carboxyl compounds are known in the art. Reference is made to CA 93:95691h where it is disclosed that these compounds are used as monomers to form polymers by polycondensation with aromatic difunctional compounds. There is no suggestion that the compounds or derivatives of them could be vacuum evaporated to form useful layers for optical devices.

Useful foramido and carbamoyl groups are

2 represented by the formulae -NHCO and

-CONR 2R3 respectively, wherein 2 and R3 are independently selected from the group consisting of unsubstituted and substituted aliphatic, aromatic and heterocyclic groups such that the molecular weight of the compound is less than about 1000.

Useful aliphatic groups include alkenes such as ethyl, propyl and nonyl; branched aliphatic groups such as 2,2-dimethyl propyl; cycloaliphatic such as cyclohexyl; substituted aliphatic such as aliphatic substituted with halogen, alkoxy, cyano and aromatic groups such as perfluoropropyl, 2-methoxyethyl and phenyl methyl; and unsaturated aliphatic groups such as 2-propenyl and 1-cyclohexenyl.

Useful aromatic groups include phenyl and naphthyl and substituted aromatic such as aromatic substituted with halogen, alkyl, cyano, alkoxy and hydroxy such as 4-methoxy phenyl and 3,4-dichloro phenyl.

Useful heterocyclic groups include pyridyl, furanyl, thiophenyl, quinolyl and piperidyl; and substituted heterocyclic such as heterocyclic substituted with alkyl, halogen and alkoxy such as

5-butylpyridyl.

Heterocyclic groups derived from amino or carboxyl groups are those groups that can be formed by reacting the amino or carboxyl group with another reagent to form the heterocycle. Useful groups therefore include the following, which can be substituted, for example, with aliphatic groups; halogen; alkoxy and nitro:

The symmetrically substituted compounds, that is R = R , are made starting with nitro phthalic anhydride. This is reacted with a nitroaniline to give a dinitro-N-phenyl—phthalimide. This in turn is reduced to the corresponding diamino compound which is then reacted with the oxychloride of the desired side chain.

The similar unsymmetrical compounds are made by reacting the appropriately substituted aniline with the proper nitro-phthalic anhydride followed by reduction to the corresponding amine. The amine is then reacted with the desired acid chloride.

The following compounds are illustrative of the compounds within the scope of the invention.

They were made by methods similar to the detailed method described in Example 1 below.

index

III.

One of the advantages of the described compounds is that the index of refraction can be changed by changing the side chain. In addition, with the vacuum coating technique, the compounds can be easily mixed. Thus, the index of refraction of the layer can- be carefully selected for the particular application. Still further, by providing two or more sources of different compounds in the vacuum chamber, a top-to-bottom gradient of index of refraction can be provided in the layer by varying the proportions of the compounds that are evaporated during the deposition of the layer. These properties are either difficult or impossible to provide with other methods using organic materials. Example 1: Preparation of 4-(4-bromophenylcarbon- amido)-N-(3-r4-bromoρhenylcarbonamido1- phen l')phthalimide A solution of 4—nitrophthalic anhydride (24.6 g., 0.127 mole) and 3-nitroaniline (17.5 g., 0.127 mole) in acetonitrile (300 ml) was heated at reflux for 84 hours, cooled and filtered. The solid was washed with cold acetonitrile, dissolved in acetic anhydride (200 ml), and heated at reflux for 3 hours. The reaction mixture was cooled, the solid filtered and rinsed with acetonitrile and dried. Yield of N-(3-nitrophenyl)-4-nitrophthalimide was 20.6 g. (51.7%); m.p. 245-246°. Calc . for C₁₄H₇N₃0₆: C, 53.7; H, 2.3; N, 13.4. Found: C, 53.6; H, 2.5; N, 13.5.

A solution of N-(3-nitrophenyl)-4-nitro- phthalimide (5.0 g. ) in tetrahydrofuran (300 ml) was reduced under hydrogen (45 psi) using platinum oxide catalyst (0.2 g.) for 18 hours. The solution was dried (MgSO,), filtered through Celite, and the solvent evaporated under reduced pressure to yield 4-amino-N-(3-aminophenyl)phthalimide; 3.8 g. (93.17,) ; M.P. 228-231°. Calcd. for C₁₄H_{n 3}0₂: C, 66.4; H, 4.4; N, 16.6. Found: C, 66.9; H, 4.9; N, 16.0.

To a stirred solution of 4-amino-N-(3-amino— phenyl)phthalimide (4.0 g., 0.016 mole) and triethyl— amine (3.6 g., 0.036 mole) in tetrahydrofuran (300 ml) was added dropwise a solution of 4-bromobenzoyl chloride (7.4 g. , 0.034 mole) in tetrahydrofuran (50 ml). After 1 hour the solution was filtered and the solvent was removed from the filtrate under reduced pressure. After several recrystallizations from a variety of solvents, a fluorescent impurity still remained. The solid was finally stirred in hot dichloromethane for several hours, filtered and dried in a vacuum oven overnight. TLC showed no more fluorescent impurity. Tield 2.22 g. (22.47.). m.p. >240^β. Calcd. for C28^H17^Br2^N3°4^: C,

54.3; H, 2.8; N, 6.8. Found: . C, 52.1; H, 2.4; N, 6.3.

Other compounds mentioned above were made in a similar manner. Characterizing refractive index and melting point data for these compounds arealso mentioned above. Example 2:

A series of compounds were vacuum deposited on quartz supports in a vacuum coating apparatus . The pertinent conditions for the deposition were: chamber pressure less than 1 x 10^~ mm Hg; substrate temperature was room temperature or about 22^βC; deposition rate of between 0.4 to 1.0 nm/sec; substrate height was 65 cm. The thicknesses of the films were between 0.10 μm and 1.0 μm.

The geometric thickness and the refractive index was determined_. by ellipsometry and waveguide analysis. This is described in detail in Rabolt et al, IBM J. Res. Develop. , _Vol 26 No. 2 pg. 209, 1982. The refractive indexes for compounds I through IX mentioned above were measured from these coated samples. Each of these coated samples would be useful, for example, as an optical wave guide. Industrial Applicability The present invention thus provides organic compounds which can be vacuum evaporated to produce useful optical elements.

Claims

WHAT IS CLAIMED IS:

1. Phthalimide compounds of the structure:

wherein R and R are independently selected from the group consisting of nitro, foramido groups, carbamoyl groups and heterocyclic groups derived from amino or carboxyl groups.

2. A phthalimide compound according to claim 1 wherein R and R are the same.

3. A phthalimide compound according to claim 1 wherein said compound is: 4—(4—bromophenyl- carbonamido)-N-(3-[4-bromophenylcarbonamido]phenyl)- phthalimide.