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A series of solvent-free FeII compounds with the same anionic [FeL2]2− center were synthesized and characterized. The tuning of the spin states, SCO profiles and critical temperatures was realized by the organic cations change.

As a molecular unit of intracellular energy transfer, adenosine triphosphate (ATP) is significant for maintaining the energy balance in living cells and thus monitoring cellular ATP is important to assess cellular physiological functions. However, effective monitoring of cellular ATP still faces challenges owing to the similarity of ATP to other nucleoside polyphosphates. Herein, yellow emissive single-layered graphene quantum dots (s-GQDs) with dual recognition sites including π-conjugated single sheets and positively charged sites were developed. The s-GQDs exhibit a good mitochondria targeting ability and respond only to purine nucleotides and show good selectivity in discriminating tri-, di- and monophosphate nucleotides. The good selectivity should be attributed to the concurrent effect of π-π stacking and electrostatic interactions between filmy layered positive s-GQDs and negative purine nucleotides. Owing to the mitochondria targeting ability and dual recognition sites of the s-GQDs, the mitochondrial ATP fluctuation resulting from the activation and suppression of ATP in living cells has been successfully monitored.

Clear doughnut-shaped far-field scattering patterns (DNSPs) for gold regular hexagonal nanoplates (AuHNPs) larger than 500 nm (distance between the two opposite edges) have been observed by dark-field microscopy imaging. This phenomenon was attributed to the edge effect, which can be further applied for reaction process monitoring.

Nitrogen-doped carbon dots (CDs) have attracted increasing attention in the field of biochemistry and biosensors due to their high emission efficiency. Herein, Bombyx mori silk, natural fibres composed by two fibroin brins and conglutinated by sericin binder, has a high content of nitrogen, was used as raw material in the coupling of citric acid to prepare nitrogen-doped CDs using a facile one-step hydrothermal route. The as-prepared nitrogen-doped CDs are uniform with an average particle size of 5.6 nm, emit blue fluorescence with the quantum yield of 61.1%, and maintain photochemical stability in high salt concentrations and in most organic solvents. Binding experiments of the as-prepared CDs with metal ions show that the hydroxyl groups on their surface play very important role in the blue fluorescence emission, which can easily bind with Fe3+ as the consequence of fluorescence quenching, making a method for Fe3+ detection developed with high selectivity and sensitivity.

Host–guest carbon dots (G@CDots) represent a new platform in the rapidly advancing and expanding research field of carbon “quantum” dots or carbon dots, enabling the development of novel carbon hybrid nanostructures of unique and/or advantageous properties and capabilities beyond those of conventional carbon dots. In this study, the red/near-IR emissive dye nile blue (NB) was selected as the guest, and NB@CDots were prepared in a microwave-assisted one-pot thermal carbonization synthesis with oligomeric polyethylene glycols (PEGs) as the precursor and also surface passivation species in the resulting host–guest dots. The NB@CDots exhibited unique and/or favorable characteristics, including especially the bright red/near-IR fluorescence emissions, with the observed fluorescence quantum yield due to the guest nile blue species more than an order of magnitude higher than that of free nile blue molecules, all in aqueous solutions. The higher fluorescence intensities were coupled with a longer fluorescence lifetime, and also accompanied by excellent photochemical stability, making the NB@CDots high-performance fluorescence probes for bioimaging-sensing and related applications. Indeed, their potential in this regard was explored and demonstrated in the fluorescence imaging of live stem cells. The NB@CDots were also evaluated in cytotoxicity assays, and the results suggested their being nontoxic. Excellent opportunities in further development of the host–guest carbon dots platform for high-performance yet nontoxic fluorescence probes are discussed.

Hexagonal boron nitride nanosheets (BNNSs) possess ultimate thermal and chemical stabilities and mechanical strengths. However, the unmodified BNNSs are hydrophobic and insoluble in water, which hinders their use in many technological areas requiring aqueous compatibility. In this work, h-BN was treated with molten citric acid to produce aqueous dispersible boron nitride sheets (ca-BNNSs). The resultant ca-BNNSs were used to fabricate ca-BNNS/polyacrylamide (i.e., BNNS2.5/PAAm) nanocomposite hydrogels, targeting high water retentivity and flexibility. The BNNS2.5/PAAm hydrogel (initially swollen in water) largely remained swollen (water content ∼94 wt%) even after one-year storage under ambient conditions. Importantly, the swollen BNNS2.5/PAAm hydrogel (water content ∼95 wt%) was highly flexible. Its elongation and compressive strength exceeded 10,000% and 8 MPa at 97% strain, respectively. Moreover, the aforementioned hydrogel recovered upon the removal of compression force, without obvious damage. The substantially improved water retentivity and flexibility revealed that BNNSs can serve as a promising new platform in the development of high-performance hydrogels.

A novel two-component organogel system based on acid-base interaction showed flexibility, high-transparency and self-healing properties with enhanced viscoelasticity. Meanwhile, the two-component gelator displayed room-temperature phase selective gelation of aromatic solvents from aromatic solvents/water mixtures in powder form and excellent dye removal ability.