Ruthenium based organometallic catalysts for CO2 hydrogenation: a decade update
Debashis Chakraborty*, Rima Das*
Inorg. Chim.Acta 2026, 597, 123154.
Ring-Opening Copolymerization
ROCOP: turning CO2 into polymer.
Carbon dioxide is an abundant, non-toxic and renewable C1 feedstock. Copolymerized with an epoxide, it becomes the backbone of an aliphatic polycarbonate — carbon that stays out of the atmosphere and does useful work.
The reaction
In ring-opening copolymerization, an epoxide and a second monomer are enchained alternately. Two families matter to us:
- Epoxide + CO2 → aliphatic polycarbonates. Cyclohexene oxide with CO2 gives poly(cyclohexene carbonate), PCHC.
- Epoxide + cyclic anhydride → fully alternating polyesters, giving access to backbones that ROP alone cannot reach.
The competing reaction — formation of the five-membered cyclic carbonate instead of polymer — is what a good catalyst has to suppress. Selectivity, not just activity, is the design target.
Our contribution
- Chiral main-group catalysts. Proline-derived Zn(II) and alkyl Al(III) compounds for efficient and controlled ROCOP of cyclohexene oxide with cyclic anhydrides.
- Organocatalytic routes. A simple organocatalyst for the ROCOP of epoxide and CO2 to aliphatic polycarbonates — the subject of a granted Indian patent.
- Bimetallic systems. Binuclear Co, Ni, Cu and Zn complexes bearing bis-benzoxazole phenoxide ligands.
- Unsymmetrical phenoxy-imine scaffolds. Zn(II), Al(III) and Mg(II) compounds giving tacticity control in ROP and activity in ROCOP of epoxides with CO2.
From the bench
Watch the chemistry happen.
PCHC synthesis
Poly(cyclohexene carbonate) formed by the ring-opening copolymerization of cyclohexene oxide with carbon dioxide — the reaction at the center of our CO2 utilization work.
Recorded in the group's laboratory at the Department of Chemistry, IIT Madras.
Selected publications
ROCOP and CO2 in our published work.
14 of 124 papers touching copolymerization, CO2 utilization and polycarbonates.
Chiral Proline-derived Zn(II) Complexes as Catalysts for Ring-Opening Polymerization and Ring-Opening Copolymerization Reactions
Ranay Kumar Ray , Manoj Kumari , Kartik Chandra Mondal*, Debashis Chakraborty*
Polym. Chem. 2026, 17, 758-769.
Efficient and Controlled Ring-Opening Copolymerization of Cyclohexene Oxide with Cyclic Anhydrides Catalyzed by Proline-based Chiral Alkyl Al(III) Compounds
Ranay Kumar Ray, P. K. Sudhadevi Antharjanam, Debashis Chakraborty*
Faraday Discuss, 2026, 262, 191–211.
Salen Derivatives of Zr(IV) as Efficient Catalysts for the Ring-Opening Copolymerization of Epoxides with Anhydrides
Sathish Thanigachalam, Ranay Kumar Ray, Madhvesh Pathak*, Debashis Chakraborty*
Eur. J. Inorg Chem. 2026, 0, e202500510.
Isolation and characterization of carbene supported air stable Co(II)-radical complexes with bileptic redox non-innocent ligands: stability, bonding, ring-opening copolymerization studies and photo-catalytic ring cyclization activity
Sujit Das, Sangita Mondal, Sonam Suthar, Ranay Kumar Ray, Karunamayee Mondal, Avany A. Raveendran, Subuhan Ahamed, Chandan Maji, Mahiuddin Baidya,* Björn Schwarz,* Debashis Chakraborty,* Liviu Ungur*, Kartik Chandra Mondal*
Dalton Trans. 2025, 54, 11182–11192.
Mononuclear and dinuclear tetravalent zirconium compounds as catalysts for the synthesis of aliphatic polyesters and aliphatic polycarbonates
Sriparna Sarkar, Sourav Singha Roy, P. K. Sudhadevi Antharjanam, Debashis Chakraborty*
Polymer 2025, 329, 128496.
Mononuclear phenoxy-imine Mg(II) compounds as catalysts for the ring-opening copolymerization of epoxides with CO2
Sourav Singha Roy, Sriparna Sarkar, Nikitha Srinivasan, P. K. Sudhadevi Antharjanam, Sooraj Kunnikuruvan*, Debashis Chakraborty*
Mater. Today Chem. 2024, 41, 102330.
Phenoxy-imine supported hexacoordinate tetravalent titanium compounds: Synthesis, characterization and catalytic applications for ROP and ROCOP reactions
Sriparna Sarkar, Sourav Singha Roy, Shobhana Krishnaswamy, Debashis Chakraborty*
Eur. Polym. J. 2024, 216, 113281.
Group 13 metal compounds as catalyst for the homopolymerization of epoxides
Sriparna Sarkar, Sourav Singha Roy, Debashis Chakraborty*
J. Polym. Res. 2024, 31, 14-21.
Bimetallic Al(III) compounds as catalysts for the synthesis of biodegradable polyesters and polycarbonates
Sourav Singha Roy, Sriparna Sarkar, P.K.Sudhadevi Antharjanam, Debashis Chakraborty*
Eur. J. Org. Chem. 2023, 26, e202300371.
Ring-opening copolymerization of CO2 with epoxides catalyzed by binary catalysts containing half salen aluminum compounds and quaternary phosphonium salt
Sourav Singha Roy, Sriparna Sarkar, P.K.Sudhadevi Antharjanam, Debashis Chakraborty*
Mol. Catal. 2023, 540, 113053-113066.
Iodine and alkali metal alkoxides: A simple and versatile catalyst system for fully alternating polyesters synthesis from phthalic anhydride and epoxides
Anjaneyulu Kummari, Sreenath Pappuru, Sourav Singha Roy, Debashis Chakraborty*
Polym. Chem. 2022, 13, 4684-4691.
Co2O3 and MnO2 as inexpensive catalysts for the ring‑opening polymerization of cyclic esters
Mrinmay Mandal*, Debashis Chakraborty*
J. Polym. Res. 2021, 28, 52-60.
Metal-free Lewis pair catalyst synergy for fully alternating copolymerization of norbornene anhydride and epoxides: Biocompatible tests for derived polymers
Anjaneyulu Kummari, Sreenath Pappuru, Piyush Kumar Gupta, Debashis Chakraborty*, Rama Shanker Verma
Mater. Today Commun. 2019, 19, 306-314.
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We collaborate with academic and industrial partners on carbon utilization and polycarbonate process development.