# US 11,999,760 B1 · Photoswitchable isomerization of novel sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene

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- Number: US 11,999,760 B1
- Document ID: US11999760B1
- Status: Granted
- Kind: B1
- Application number: 18/539,786
- Filed: 2023-12-14
- Granted: 2024-06-04
- Earliest claimed: 2023-12-14
- Assignees: King Faisal University
- Applicants: King Faisal University
- Inventors: Obadah Subhi Abdel-Rahman
- Web page: https://patentgrep.com/patent/US11999760B1

## CPC

- C07F 7/081: {comprising at least one atom selected from the elements N, O, halogen, S, Se or Te}
- C07F 7/20: Purification, separation
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)

## Abstract

A reversible photo-switchable isomerization of novel sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene and its synthesis.

## Claims

### Claim 1

A sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene complex having the formula I:

### Claim 2 (depends on 1)

The sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 1, wherein the compound is an orange crystalline solid.

### Claim 3 (depends on 1)

A method of making the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 1, the method comprising:
adding 2,2′,6,6′-tetraisopropyl-4,4′-diiodoazobenzene, triphenylphosphine and trimethylsilylacetylene (TMSA) in dry triethylamine to a solution of CuI and PdCl2(PPh3)2 in tetrahydrofuran (THF) to obtain a reaction mixture;
stirring and heating the reaction mixture for at least about 8 hours to obtain a precipitate;
evaporating solvent under vacuum and dissolving the precipitate in CH2Cl2;
filtering dissolved precipitate to purify precipitate; and
obtaining the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene.

### Claim 4 (depends on 3)

The method of making the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 3, wherein additional TMSA is added for complete reaction of 2,2′,6,6′-tetraisopropyl-4,4′-diiodoazobenzene.

### Claim 5 (depends on 3)

The method of making the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 3, wherein the precipitate is purified over silica gel.

### Claim 6 (depends on 3)

The method of making the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 3, wherein the filtered precipitate is purified using column chromatography.

### Claim 7 (depends on 6)

The method of making the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 6, wherein the column chromatography is performed using petroleum ether and dichloromethane in a 9:1 ratio as an eluent.

### Claim 8 (depends on 3)

The method of making the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene of claim 3, wherein the sterically hindered 2,2′,6,6′-tetraisopropyl-4,4′-bis((trimethylsilyl)ethynyl)azobenzene is obtained as an orange crystalline solid.