# Most-cited Chemistry papers of 2021, with free PDFs

The 25 most-cited Chemistry research papers published in 2021, ranked by citations in OpenAlex, with their original abstracts and free PDFs where available.

1. [The PRIDE database resources in 2022: a hub for mass spectrometry-based proteomics evidences](https://nerdi.pages.dev/paper/W3208691473) · 6,206 citations
2. [CrystalExplorer : a program for Hirshfeld surface analysis, visualization and quantitative analysis of molecular crystals](https://nerdi.pages.dev/paper/W3159829212) · 5,135 citations
3. [The HITRAN2020 molecular spectroscopic database](https://nerdi.pages.dev/paper/W4200599926) · 2,495 citations
4. [Metallaphotoredox: The Merger of Photoredox and Transition Metal Catalysis](https://nerdi.pages.dev/paper/W3212204911) · 1,756 citations
5. [Metal–Organic Framework-Based Hierarchically Porous Materials: Synthesis and Applications](https://nerdi.pages.dev/paper/W3185024652) · 1,644 citations
6. [White Analytical Chemistry: An approach to reconcile the principles of Green Analytical Chemistry and functionality](https://nerdi.pages.dev/paper/W3132104108) · 1,296 citations
7. [Electrocatalysis as an enabling technology for organic synthesis](https://nerdi.pages.dev/paper/W3164483471) · 1,283 citations
8. [The Current Status of MOF and COF Applications](https://nerdi.pages.dev/paper/W3161898781) · 1,202 citations · Free PDF
9. [iProX in 2021: connecting proteomics data sharing with big data](https://nerdi.pages.dev/paper/W4200608270) · 1,134 citations
10. [Recent Advances in Catalytic Asymmetric Construction of Atropisomers](https://nerdi.pages.dev/paper/W3143666723) · 1,051 citations
11. [Photoredox-Catalyzed C–H Functionalization Reactions](https://nerdi.pages.dev/paper/W3204003150) · 988 citations
12. [Two-Dimensional Metal-Organic Framework Materials: Synthesis, Structures, Properties and Applications](https://nerdi.pages.dev/paper/W3132590780) · 932 citations
13. [Metal–Organic Frameworks for Drug Delivery: A Design Perspective](https://nerdi.pages.dev/paper/W3127881081) · 921 citations
14. [Organic Electrochemistry: Molecular Syntheses with Potential](https://nerdi.pages.dev/paper/W3134055974) · 861 citations
15. [Visible Light-Induced Transition Metal Catalysis](https://nerdi.pages.dev/paper/W3202186145) · 860 citations
16. [Reducing the resistance for the use of electrochemical impedance spectroscopy analysis in materials chemistry](https://nerdi.pages.dev/paper/W3194172516) · 845 citations
17. [C–H Activation: Toward Sustainability and Applications](https://nerdi.pages.dev/paper/W3128724272) · 833 citations
18. [Molecular Imprinting: Green Perspectives and Strategies](https://nerdi.pages.dev/paper/W3168193264) · 787 citations
19. [Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry](https://nerdi.pages.dev/paper/W3188805634) · 783 citations
20. [Proton-Coupled Electron Transfer Guidelines, Fair and Square](https://nerdi.pages.dev/paper/W3118324056) · 715 citations
21. [Twisted intramolecular charge transfer (TICT) and twists beyond TICT: from mechanisms to rational designs of bright and sensitive fluorophores](https://nerdi.pages.dev/paper/W3205818211) · 715 citations
22. [Chiroptical Properties of Symmetric Double, Triple, and Multiple Helicenes](https://nerdi.pages.dev/paper/W3119374153) · 701 citations
23. [Metal–organic frameworks as photoluminescent biosensing platforms: mechanisms and applications](https://nerdi.pages.dev/paper/W3132706619) · 699 citations
24. [Evolution of water structures in metal-organic frameworks for improved atmospheric water harvesting](https://nerdi.pages.dev/paper/W3206148627) · 695 citations
25. [Applications of Halogen-Atom Transfer (XAT) for the Generation of Carbon Radicals in Synthetic Photochemistry and Photocatalysis](https://nerdi.pages.dev/paper/W3215716308) · 628 citations

Canonical page: https://nerdi.pages.dev/papers/chemistry/most-cited-2021