Synthesis And Catalytic Properties Of Chiral Carbon Based Nanomaterials

Chirality,as one of the most fascinating occurrences in the nature,has attracted extensive attention for its key roles in many fields of scientific endeavour ranging from chemistry,biochemistry to pharmacology and medicine.Over the past several years,considerable efforts have been devoted to the synthesis of chiral nanoparticles inspired by prospects for their potential applications,among which chiral metal nanoparticles are particularly outstanding due to their plasmonic bands and chemical stability.However,the toxicity and high cost of the metals may hamper their applications in large-scale commercialization.Thereby,it is emergent to fabricate and develop new types of metal-free chiral materials with marvellous performance.Recently,carbon has aroused extensive interest owing to their abundant entity,low toxicity and low cost.Carbon dots,as a new class of carbon nanomaterials with size below10 nm,have become a rising star in nanocarbon family due to their biocompatibility,low toxicity,photostability,strong fluorescence and so on.In addition,graphene and its derivatives,as another interesting carbon nanomaterials,have also captured ever-increasing attention as a result of their outstanding magnetic,thermal,mechanical and electronic properties.Thus,after incorporated with chirality,carbon dots and graphene can exhibit more novel properties.This paper introduces the preparation of chiral nitrogen and sulfur co-doped chiral carbon quantum dots?L-CQDs,D-CQDs?,chiral carbon dots?L-CDs,D-CDs?and chiral functionalized graphene oxide?L-GO,D-GO?.The structures of these materials were characterized with various instruments.In addition,their chiral structures and catalytic activities were also studied.The detailed information was shown as follows:?1?L-CQDs and D-CQDs were synthesized via a hydrothermal method from L-cysteine and D-cysteine with the help of NaOH.The obtained chiral CQDs show chiral signals with high symmetry located at 212 and 240 nm,where the first one is ascribed to the inheritance of cysteine and the latter one is corresponding with?-?*conjugation of sp² hybridization of carbon network.The chiral CQDs were demonstrated that their photoluminescence is independent with chirality for the first time.In addition,these chiral CQDs also show highly enantioselective electrochemical recognition and electrocatalytic ability toward small chiral molecules with right configuration.?2?L-CDs and D-CDs were synthesized by a facile one-step alkali-assistant electrochemical method from cysteine.The obtained chiral CDs show chiral signals at215,248 and 293 nm with high symmetry.In order to understand the mechanism of chiral structure,a serious of samples prepared with different time were characterized through fourier transform infrared?FT-IR?,Raman,UV-vis absorption,circular dichroism?CD?and X-ray photoelectron spectroscopy?XPS?.The results suggest that the first signal is attributed to the inheritance of cysteine,and the last two may be recognized as?-?*conjugation of sp²-hybridized carbon network and the generation of S-S bond to induce spatial configuration,respectively.Combining with chirality,stability and biocompatibility,these chiral CDs were firstly demonstrated to be capable of selective tuning the activity of laccase,in which case the L-CDs can improve activity of enzyme up to 20.2%,while the D-CDs decrease the activity to 10.4%.?3?L-GO and D-GO were synthesized through a one-step hydrothermal method from GO and cysteine.During hydrothermal process,cysteine can translate to cystine and combine with GO via covalent bonds.The chirality was introduced into the system with non-decreasing CD signals.Having the advantages of chirality,well biocompatibility,excellent stability and conductivity,the chiral GO exhibits great enantioselective recognition toward chiral tartaric acid.In addition,chiral GO also shows the excellent recognition toward tryptophan?Trp?with the detection limit of 1.6×10^-5M for L-GO and2.3×10^-5M for D-GO.