The 73rd Annual Congress of the Slovak and Czech Chemical Societies, held on 6–10 September 2021 in High Tatras, Slovakia, attracted more than 400 participants who presented and discussed a wide range of topics and achievements of chemistry research in Slovakia and Czech Republic. The program of the congress included an exclusive plenary lecture by Dr. Pavol Čekan on the topic of Development of quantitative and multiplex diagnostic technologies and application. He was awarded the Gold Medal of the Slovak Chemical Society for his world-wide contribution to chemical research and its applications for the societal benefit. Furthermore, 5 invited lectures, 160 lectures, and 200 posters were presented in 7 scientific sections during the congress. The 73rd Annual Congress of the Slovak and Czech Chemical Societies was also an opportunity to acknowledge the work of diligent PhD students and young chemists. In this respect, the organizer handed over various awards such as Marta Sališová Prize for the best presentation of PhD students and young chemists under 30 years of age and prizes within the competitions for the best posters of young chemists including IUPAC Poster Prizes, Dean's Award of the Faculty of Chemical and Food Technology of Slovak University of Technology in Bratislava, Dean's Award of the Faculty of Natural Sciences of the Pavol Jozef Šafárik University in Košice, as well as Dean's Award of the Faculty of Natural Sciences of the Comenius University and Rector's Award of the Comenius University in Bratislava.

Despite the fact that our congress was held during the pandemic situation under limited conditions and regime, we are very glad that it finally took place and many participants from various academic institutions and chemical companies from Slovakia and Czech Republic took part in it. This Special Issue, entitled “Selected Papers from the 73rd Annual Congress of the Slovak and Czech Chemical Societies”, is intended to serve as a summary of the selected papers, the content of which was presented by mostly younger participants of this congress, either as a lecture or poster. The contributions aim to include a cross-section of various chemistry areas and disciplines and ensure a thorough exchange and dissemination of scientific information, knowledge, and experience among a broad community of chemists. From this point of view, we are convinced that the proposed issue can also be interesting for the readers of this interdisciplinary chemistry journal.

On behalf of the Slovak Chemical Society, as the organizer of the 73rd Annual Congress of the Slovak and Czech Chemical Societies, but at the same time as the guest editors of this issue, we would like to thank the Editor-in-Chief of Monatshefte für Chemie—Chemical Monthly, Prof. Dr. Peter Gärtner, for his kind support in the preparation of this special issue. Finally, we cordially thank all the authors for their contributions and the reviewers for their valuable comments that improved the quality of the papers in this special issue.

Enjoy reading this special issue.