Cyclophanes as Emerging Materials — From Synthesis To Functions

Cyclophanes, in general, are coined to name any small or larger cyclic system containing methylene-bridged -[CH2]n- aromatic ring (be they all-carbon or heteroaromatics); hence, a diverse class of molecular systems can be referenced as cyclophanes. It was Nobel laureate Donald James Cram who first suggested the name "cyclophane" for this class of compounds, which have since become more sophisticated with increased functionality (as chiral ligands/catalysts, precursors/monomers, materials, and functional systems, molecular devices) and morphed with time. The aesthetically appealing and stereochemically remarkable molecular architecture of cyclophanes, their mechanisms of formation, and unusual physicochemical functions are of substantial importance from the perspective of fundamental scientific curiosity to a wide range of applications-driven research across chemical sciences and technology. In recent years, meeting the demands of an ever-changing research landscape, cyclophane chemistry has inevitably evolved from molecules to new materials that involve cyclophanes, as witnessed by the dramatic increase in breakthrough research which prompted this dedicated Special Issue of Advanced Functional Materials' Cyclophanes as Emerging Materials — From Synthesis to Functions' highlighting research contributions from best-known leading experts in the field that beautifully illustrates the ever-expanding scope of cyclophanes from a materials sciences perspective. The spectacular and fast-growing developments in the field, which are truly multi-disciplinary and cut across several interrelated disciplines at the chemistry–material science interface, are propelled by inputs from experts in synthetic chemistry, polymer chemistry, surface science, optoelectronics, photophysics, and material engineering. This Special Issue highlights new paradigms and covers global developments focusing on technologically-relevant cyclophane-based material applications. The progress is reflected in the following thematic collection of 22 inspirational articles, each providing instructive details of the most recent research in the fast-moving field of cyclophanes and an assessment of a future to look forward to expanding the bounds of this exciting field is provided. This collection includes Perspectives, Reviews, and Personal Account-type reports presenting extensive and insightful discussions and several inspiring research articles describing collaborative interests in emerging applications that offer a hopeful vision of where research might be heading. The chemistry of cyclophanes is still under active investigation and will continue to blossom, which opens the possibility for a sequel in due time. We believe the future of cyclophane chemistry will benefit from interdisciplinary efforts and melding cross-disciplinary viewpoints with genuinely fresh perspectives. The partnership of scientists, engineers, and entrepreneurs will play a decisive role in bringing breakthroughs from labs to translational opportunities. This special issue of inspirational articles will be a valuable source in scientific research and teaching endeavors that will stimulate further explorations to keep pushing the boundries of the cyclophanes chemistry. It was the objective of the guest editors to create a one-stop reference for chemists, material scientists, and the broader scientific community interested in cyclophane chemistry. To understand the full scope, we encourage you to read it in full. We are pleased to serve as the Guest Editors for this Special Issue and express our appreciation for this opportunity on the occassion of the 75th anniversary of the [2.2]paracyclophane and to highlight the recent achievements in cyclophanes chemistry. We thank all the individual authors for their outstanding research and contributions, making this up-to-date collection of articles possible. We are thankful to all the reviewers for their enormous support in evaluating research articles, and their input to the peer-review process is much appreciated. We also acknowledge the dedicated and excellent production team of Advanced Functional Materials of Wiley-VCH for their efforts in bringing together and spreading this Special Issue far and wide, especially the Editors Jörn Ritterbusch and Marc Zastrow; their assistance on the subject of this special issue is appreciated with thanks. We welcome you to the amazing "World of Cyclophanes" and invite you to explore your fascinating interests in this exciting, diverse collection of articles: "Cyclophane as Emerging Materials — From Synthesis to Functions." Thanks for reading! The authors declare no conflict of interest. Zahid Hassan, Ph.D., studied chemistry at the HEJ Research Institute of Chemistry, at the Institut für Organische Chemie, Leibniz Universität Hannover, and received Ph.D., at the Institut für Organische Chemie (Leibniz-Institut für Katalyse), Universität Rostock, Germany. After an IBS Fellowship at the Centre for Self-Assembly and Complexity, POSTECH, he held a Faculty Position as Assistant Professor of Chemistry at the University of Nizwa, and then moved to Karlsruher Institüt für Technologie (KIT) in 2017, where he has led a research team at the Institut für Organische Chemie (IOC) and Institute of Functional Interfaces (IFG) at the KIT on synthesis methods development, chiral ligands/catalysts, materials synthesis via molecular self-assembly and understanding the chemical aspects behind system-level functions. Joerg Lahann, Ph.D., is the Wolfgang Pauli Collegiate Professor of Chemical Engineering and Director of the Biointerfaces Institute at the University of Michigan. The Lahann Lab studies advanced polymers for drug and gene delivery and surface engineering. Current research areas include synthetic protein nanoparticles, CVD polymerization, and 3D jet writing. Lahann published over 300 research papers and contributed to 50 patents/patent applications. Lahann is an elected Fellow of the National Academy of Inventors and the American Institute of Medical and Biological Engineering, has been selected by Technology Review as one of the top 100 young investigators, and is the recipient of the Nanoscale Science and Engineering Award, an NSF-CAREER award, and two Idea Awards from the Department of Defense. Stefan Bräse studied in Göttingen, Bangor (UK), and Marseille and received his Ph.D. with Armin de Meijere in Göttingen. After postdoctoral research at Uppsala University (Jan E. Bäckvall) and The Scripps Research Institute (K. C. Nicolaou), he began his career at the RWTH Aachen (with D. Enders). In 2001, he finished his habilitation and moved to the University of Bonn as a professor of chemistry. Since 2003, he has been a professor at KIT and director of the Institute of Biological and Chemical Systems-Functional Molecular Systems at KIT. His research interests include asymmetric processes, combinatorial methods for biologically active compounds, and synthetic functional materials.