“COSY” is the acronym for “Confined Molecular Systems: from the new generation of materials to the stars”, a COST Action (acronym for European Cooperation in Science and Technology). It is basically a platform for cooperation between research groups in Europe that have nationally funded projects in confined molecular systems. The COST Action “COSY” aims to provide computational and experimental building blocks for a fundamental understanding of confined molecular systems in order to be able to control them. The platform already brings together more than 480 members from around 45 member countries of the European Union. It is structured in five strongly correlated working groups whose objectives range from a first-principles description of the interaction between a molecule and its environment, including the interstellar medium, to the synthesis of new materials with theranostics applications, energy conversion, and photocatalysis.

We cordially invite all the members of the COST Action CA21101 (“COSY”), as well as all interested parties, to CSIC Central Campus, Madrid, for the Fourth and Final General Meeting of our COST Action. The COST Action is dedicated to a better understanding and recognition of issues relevant to the experimental and theoretical characterization of confined molecular systems, from those relevant in new materials research, to those playing a key role in astrochemistry. The Fourth General Meeting of the COST Action “COSY” will gather scientific sessions addressing the five Working Groups (WGs). A Management Committee Meeting will be celebrated during the afternoon of the last day (29 April). The General Meeting will provide an opportunity for the members of the Action’s five Working Groups (WGs) to undertake collaborations addressing the goals of the Fourth Grant Period of the COST Action. For this purpose, the meeting will host dedicated sessions covering all WGs. This Meeting will be central to promote the deliverables of the COST Action “COSY”. In this way, the program will include overview lectures (30 minutes long) by the leaders of the five Working Groups:

• Working Group 1: Fundational, theoretical, and experimental investigation of the formation of molecules and matter in the interstellar medamental studies of molecular interactions: new methods, benchmarks on confined systems (Working Group 1 Leader: Piotr Zuchowski).
• Working Group 2: Molecular motion in porous, biomolecular and environmental-confined systems via advanced simulation methods (Working Group 2 Leader: Sonja Grubisic).
• Working Group 3: Advanced theory and experiments on confined metal/oxide clusters for catalytic and nanotechnology applications (Working Group 3 Leader: Alessandro Fortunelli).
• Working Group 4: Time-resolved and reactive dynamics, spectroscopy, and simulations of molecules in He nanodroplets (Working Group 4 Leader: Marcel Mudrich).
• Working Group 5: Computium and in planetary and solar atmospheres (Working Group 5 Leader: Lauri Halonen).

The program will also include invited lectures (25 minutes long), reporting active joint projects between the Action members, including those related to STSMs, and hot topic presentations (15 minutes long). We encourage the youngest researchers to present hot topic posters preceded by 2-minute flash presentations. Two RSC PCCP Poster prizes will be awarded.