Celebrating a Century of Excellence in Chemistry at Xiamen University

Established in 1921, Chemistry at Xiamen University (XMU) has been the national leader in education in chemistry and advancing the frontier of chemistry in China. Its inclusive and vibrant academic environment encourages faculty and students to unleash creativity, delve into details, and value collaborations. This rich culture roots from the legacy of predecessors such as Prof. Jia-Xi Lu, the former president of the Chinese Academy of Sciences (CAS) who himself was an undergraduate in XMU Chemistry (XMUC) and worked at Caltech with Prof. Linus Pauling from 1939 to 1945.

Carrying on Lu's tradition in physical chemistry, XMUC particularly emphasizes developing rigorous scientific approaches to obtain mechanistic understanding at a very fundamental level. XMUC is proud of numerous ground-breaking methodologies and first-of-its-kind instrumentations developed in the department, thanks to the persistent and resilient efforts of its members.

XMUC currently houses several major national scientific research platforms, including the State Key Laboratory of Physical Chemistry of Solid Surfaces (PCOSS), which has been ranked at the highest level in all national appraisals since its foundation in 1987, and the Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), one of only two of its kind in chemistry nationally.

To celebrate the 100th anniversary of XMUC, 50 papers published in the last 5 years in Royal Society of Chemistry (RSC) journals, including Chem. Soc. Rev., Chem. Sci. and Chem. Commun., by the XMUC members are collected in this virtual issue to reflect the research activities of XMUC in the frontiers of chemistry.

(1) XMUC is developing instrumental, analytical and computational methods for studying complex chemical systems, ranging from clusters, nanomaterials, catalytic surfaces and electrode electrolyte interfaces, and fabricating novel nanostructures.

XMUC is one of the most important institutions in plasmon-enhanced spectroscopy. The three selected review articles systematically introduce: the theories of surface-enhanced Raman spectroscopy (SERS) and the strategies for optimizing SERS substrates (DOI: 10.1039/c7cs00238f); the existing problems of SERS and the approaches to realize practical applications (DOI: 10.1039/d0sc00809e); and tip-enhanced Raman spectroscopy for studying surfaces and interfaces (DOI: 10.1039/c7cs00206h). The selected original articles reported: a method to accurately calculate the infrared and Raman spectra in electrochemical systems (DOI: 10.1039/c9sc05429d); a shell-isolated nanoparticle-enhanced Raman study of the bond cleavage of N719 dye molecules on TiO₂(hkl) (DOI: 10.1039/d0sc00588f); a shell-isolated concept to enhance emission (DOI: 10.1039/c7cs00169j); and a combined in situ SERS and mechanically controllable break junction study of the origin of the long-standing discrepancy in single-molecule conductance (DOI: 10.1039/c8sc00727f). Other characterization techniques were also developed, for example, the conductance measurement of single-molecule junctions to reveal the quantum interference effects in protonated azulene derivatives (DOI: 10.1039/c7sc01014a), a broadband sum frequency generation spectroscopy study of CO on a Pt electrode (DOI: 10.1039/d0cc02469d), and Glovebox-AFM force curve measurements of the effect of water on the interfacial structure of mica and an ionic liquid (DOI: 10.1039/d0cc06587k).

In addition to the above characterization techniques, new techniques were developed to fabricate micro/nanostructures. In the selected review article, the state-of-the-art in electrochemical micro/nano-machining techniques for direct writing, surface planarization and polishing, and 3D-MNS fabrication are overviewed (DOI: 10.1039/c6cs00735j). The two original articles reported a direct electrochemical nanoimprint lithography method with the understanding of the chemical mechanism of metal assisted chemical etching in platinum and an n-type gallium arsenide (100) wafer system (DOI: 10.1039/c6sc04091h), and a low-cost nanoimprint technique based on the observed photoelectric-effect-enhanced interfacial charge transfer reactions (DOI: 10.1039/c9sc01978b).

(2) XMUC shows the great power of creating new molecules and materials with novel functions, and steering non-covalent interactions for solving fundamental chemical challenges.

The selected review article addressed the latest trends and developments in Brønsted acid-mediated reactions of ynamides (DOI: 10.1039/d0cs00474j). The selected original articles reported: concise, divergent total syntheses of five bioactive illudalane sesquiterpenes, featuring an intermolecular [2+2+2] cycloaddition, and a lactone-directed aromatic C–H oxygenation (DOI: 10.1039/c9cc00933g); the synthesis of largely π-extended rylene diimide-fused thienoacenes using a novel trisulfur radical anion (S3˙⁻)-triggered stitching thienannulation strategy (DOI: 10.1039/c9sc05332h); hydroboration of aldehydes and ketones by N-heterocyclic ylide-like germylene under mild conditions (DOI: 10.1039/c6cc08147a); the first metal-free intramolecular alkoxylation/Claisen rearrangement of a Brønsted acid-catalyzed intramolecular alkoxylation-initiated tandem sequence (DOI: 10.1039/c9sc00079h); direct reductive alkynylation of tertiary amides to propargylic amines through sequential Ir-catalysed hydrosilylation–Cu(I)-catalysed alkynylation (DOI: 10.1039/c6cc05318a); synthesis of phosphanylhydrosilylalkynes and their reaction with B(C₆F₅)₃ to produce alkenes (DOI: 10.1039/c8cc09022j); the use of pyridines containing adjacent C≡C bonds as ligand units to be integrated into the skeleton of conjugated microporous polymers for Pd-catalyzed allene hydrosilylation (DOI: 10.1039/c9cc09387g); the intramolecular C(sp³)–H/C(sp²)–H cross-coupling of 1,3-dicarbonyl compounds through Cp₂Fe-catalyzed electrochemical oxidation (DOI: 10.1039/c8cc02472c); the enantioselective photoredox reaction of α,β-unsaturated carbonyl compounds and tertiary/secondary α-silylamines by a non-precious chiral catalyst (DOI: 10.1039/c8sc01219a); a new mechanistic approach for the visible-light induced catalytic, enantioselective conjugate addition of nitrogen-based nucleophiles to acceptor-substituted alkenes (DOI: 10.1039/c7sc02031g); the halogenation of metallapentalyne to produce metallapentalenes (DOI: 10.1039/c5sc03963k), a new concept of intramolecular multi-bond strain referring to the repulsion among π bonds to reconcile the discrepancy between experimental and theoretical conjugation energies (DOI: 10.1039/c6sc00454g); and the extension of Baird's rule from conventional organic molecules to all-metal systems with σ- and π-aromaticity (DOI: 10.1039/d0cc05586g).

Non-covalent strategies were used to synthesize large molecules, including cage compounds applied to catalyze non-covalent molecular assembly (DOI: 10.1039/c9sc02412c); a series of chiral face-rotating sandwich structures was obtained without introducing any chiral substituents (DOI: 10.1039/c8sc03404d); cysteine/penicillamine-mixed peptide frameworks were designed to fold into specific regioisomers independent of primary amino acid sequences (DOI: 10.1039/c7sc03956e); a novel class of artificial disulfide-rich peptide scaffolds with precisely defined disulfide patterns was reported (DOI: 10.1039/c6sc05710a); and multi-network elastomers with a reformable sacrificial network containing mechanochemically sensitive anthracene-dimer cross-links was reported, showing persistent and reversible mechanochromism (DOI: 10.1039/c9sc02580d).

The XMUC has a long tradition in developing methods to obtain clusters and nanocrystals with well-defined structure. The selected review article addressed well-faceted noble-metal nanocrystals with nonconvex polyhedral shapes, from structure, synthesis to applications (DOI: 10.1039/c6cs00039h). The original articles report: two 34-atom metal nanoclusters revealing the importance of coordination saturation for analyzing metal nanocluster stabilities (DOI: 10.1039/c8sc03756f); and the dispersion of large sintered Au particles into uniform small nanoparticles after treatment with iodohydrocarbons (DOI: 10.1039/c5sc04283f).

As an emerging field, liquid-based porous membranes were reviewed in a tutorial way to provide a new unifying view on the state-of-the-art progress of the field to inspire frontier research in interfacial chemistry, materials chemistry, fluid mechanics, membrane science, chemical engineering, etc. (DOI: 10.1039/d0cs00347f).

(3) Combining the strengths in physical and synthetic chemistry to develop promising technologies for applications in catalysis, fuel cells, batteries, biological systems and more.

There are a number of activities in CO₂-related research. The selected review articles addressed: the advances in breaking the selectivity limitation by using a reaction coupling strategy for hydrogenation of both CO and CO₂ into C₂₊ hydrocarbons (DOI: 10.1039/c8cs00502h); and the advances in the photocatalytic and photoelectrocatalytic reduction of CO₂ with H₂O using heterogeneous semiconductor-based catalysts (DOI: 10.1039/c5cc07613g). The original articles reported: a two-dimensional light-harvesting metal–organic layer (MOL) to allow the efficient transport of excited state energies to reaction centers for enhancing the photocatalytic CO₂ reduction to CO or HCOOH (DOI: 10.1039/c9cc04594e); bifunctional catalysts for the direct conversion of syngas into lower olefins with selectivity significantly breaking the Anderson–Schulz–Flory distribution (DOI: 10.1039/c8sc01597j). There is also very active research on the photocatalytic transformation of lignocellulosic biomass in XMUC, and this field was critically reviewed with an emphasis on photocatalytic cleavage of C–O and C–C bonds in the major components of lignocellulosic biomass (DOI: 10.1039/d0cs00314j).

There are also some activities towards the development of energy storage materials, for example, a vapor grown carbon fiber (VGCF) 3D conducting host coating on a glass fiber filter was used as a lithium metal anode to inhibit dendrite growth (DOI: 10.1039/c7cc07828e) and 3D binder-free Si@Ti@TiN thin film array electrodes were fabricated for supercapacitors using deep silicon etching and magnetron sputtering (DOI: 10.1039/c8cc08219g).

There are long-standing efforts on developing methods for biomedical analysis in the XMUC. The selected review articles systematically introduced: various techniques for isolation of CTCs and single-cell analysis of CTCs at the genomic, proteomic and phenotypic level (DOI: 10.1039/c6sc04671a) and the recent progress made in sensing based on induced supramolecular aggregation–disaggregation (DOI: 10.1039/c6cc06075g). The selected original articles reported: a functional DNA crosslinked hydrogel and gold nanorods for the sensitive detection and visualization of different targets (DOI: 10.1039/c7cc01360d); a pair of water soluble and biologically interconvertible redox-responsive manganese complexes as probes in ¹H/¹⁹F MRI for detecting and imaging biological redox species (DOI: 10.1039/d0cc00778a); a responsive hetero-organelle partition and signal activable probe for detecting mitochondrial depolarization (DOI: 10.1039/c6sc04158b); a pH-sensitive multifunctional theranostic platform with ¹³¹I and ¹²⁵I radiolabeled Pd nanosheets for single photon emission computed tomography and photoacoustic tumor imaging (DOI: 10.1039/c8sc00104a); and small Pd nanosheets for effective in vitro and in vivo photothermal therapy of tumors (DOI: 10.1039/c8sc04318c).

We hope with these collected articles in this virtual issue, the readers may have a brief idea of the most recent research activities in XMUC, which may trigger future international collaborations.

Professor Jun Cheng and Professor Bin Ren

Guest Editors

---