Materials for organic electroluminescent devices
US-9515266-B2 · Dec 6, 2016 · US
Ring systems of four or more rings
Ring systems of four or more rings · Cooperative Patent Classification (CPC)
Chemical and metallurgical processes, compounds, and materials.
Related technology areas
Mapped technology topics for this CPC code.
| Metric | Value |
|---|---|
| CPC code | C07D221/18 |
| Official title | Ring systems of four or more rings |
| Display label | Ring systems of four or more rings |
| Total patents | 293 |
Filing trend
Year-over-year patent counts classified under this CPC code.
Filing activity over the last five years is declining.
| Year | Patents |
|---|---|
| 2015 | 40 |
| 2016 | 28 |
| 2017 | 34 |
| 2018 | 29 |
| 2019 | 30 |
| 2020 | 23 |
| 2021 | 28 |
| 2022 | 23 |
| 2023 | 20 |
| 2024 | 16 |
| 2025 | 18 |
| 2026 | 4 |
Representative patents
Representative publications under this CPC code from precomputed stats, or recent filings when stats are unavailable.
Polycyclic aromatic hydrocarbon compounds containing an S atom or S(=O)2 group in their basic structure
US-9505869-B2 · Nov 29, 2016 · US
Synthesis of tetracyclines and analogues thereof
US-2016340325-A1 · Nov 24, 2016 · US
Quinoid rylenedicarboximides as IR absorbers
US-9493422-B2 · Nov 15, 2016 · US
Quinacridone pigment of low amine content and method for producing same
US-2016280924-A1 · Sep 29, 2016 · US
Organic electroluminescent material and organic electroluminescent device
US-2016260907-A1 · Sep 8, 2016 · US
N-substituted indenoisoquinolines and syntheses thereof
US-2016229888-A1 · Aug 11, 2016 · US
Metal Complexes
US-2016233443-A1 · Aug 11, 2016 · US
Synthesis and use of dual tyrosyl-DNA phosphodiesterase I (Tdp1)—topoisomerase I (Top1) inhibitors
US-9402842-B2 · Aug 2, 2016 · US
Synthesis of tetracyclines and analogues thereof
US-9365493-B2 · Jun 14, 2016 · US
Traceless directing groups in radical cascades: from oligoalkynes to fused helicenes without tethered initators
US-2016145276-A1 · May 26, 2016 · US
Photoelectric conversion material, film containing the material, photoelectric conversion device, method for preparing photoelectric conversion device, method for using photoelectric conversion device, photosensor and imaging device
US-9349965-B2 · May 24, 2016 · US
Organic electroluminescent device
US-9337430-B2 · May 10, 2016 · US
Alcohol-, diol-, and carbohydrate-substituted indenoisoquinolines as topoisomerase I inhibitors
US-9328073-B2 · May 3, 2016 · US
Topoisomerase inhibitors
US-9321781-B2 · Apr 26, 2016 · US
Heterocyclic compound, organic light-emitting diode including the heterocyclic compound, and flat display device including the organic light-emitting diode
US-9312497-B2 · Apr 12, 2016 · US
SYNTHESIS AND USE OF DUAL TYROSYL-DNA PHOSPHODIESTERASE I (Tdp1) - TOPOISOMERASE I (Top1) INHIBITORS
US-2016081999-A1 · Mar 24, 2016 · US
Organic electroluminescent materials and devices
US-2016072082-A1 · Mar 10, 2016 · US
Beta-amyloid-directed multitarget compounds for the treatment of alzheimer's disease
US-9238626-B2 · Jan 19, 2016 · US
Photoelectric conversion element and method of using same, optical sensor and image sensor
US-2016013424-A1 · Jan 14, 2016 · US
Frequently asked questions
Answers are generated from the same data shown on this page.
- What is CPC C07D221/18?
- CPC C07D221/18 is the Cooperative Patent Classification code for “Ring systems of four or more rings.”
- How many patents are filed under CPC C07D221/18 (Ring systems of four or more rings)?
- Our database includes 293 publications tagged with this CPC code.
- Is patent activity under CPC C07D221/18 growing?
- Publication counts under this code: 16 in 2024 vs 18 in 2025 (latest complete years).