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The application of iron oxide quantum dots (IOQDs) in this study led to the development of a straightforward, easy, and selective approach for cytosine sensing. To examine the capability of IOQDs in detecting nucleobases, attempts have been made to gain insight into the characteristics of IOQDs, including UV/Vis spectroscopic analysis, infrared spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and powder‐XRD. We introduced IOQDs with a mean particle size distribution of 5.71 ± 0.08 nm for detecting cytosine by harnessing a turn‐on fluorescence phenomenon. The fostering fluorescence response of IOQDs was triggered in the presence of cytosine. In comparison, the presence of other nucleobases did not further induce the fluorescence signal of IOQDs. It was concluded that the hydrogen bonding bridging the carboxylate and hydroxyl groups on the surface of QDs with the amine groups of cytosine results in the elevation of IOQDs fluorescence. A potential application of luminescent IOQDs for cytosine sensing based on the cytosine‐induced fluorescence enhancement of IOQDs is proposed. Selective, sensitive, and quick response behaviours of cytosine‐induced fluorescence showed a high fluorescence augmentation towards cytosine.

A series of Al catalysts with N,N′-diaryloxalamidate and N,N′-diaryldithiooxalamidate ligands were synthesized, and their ε-caprolactone polymerization rates were determined in this study. Of the Al complexes bearing N,N′-diaryldithiooxalamidate, [PhHNCS]2Al2Me4exhibited the highest catalytic activity (conv. of poly-ε-caprolactone = 94%; [ε-caprolactone]:[[PhHNCS]2Al2Me4]:[benzyl alcohol] = 100:0.5:2 with [ε-caprolactone] = 2 M at 25 °C after 20 min), and of the Al complexes bearing N,N′-diaryldioxalamidate, [PhHNCO]2Al2Me4exhibited the highest catalytic activity (conv. of poly-ε-caprolactone = 94%; [ε-caprolactone]:[OHAl2Me4]:[benzyl alcohol] = 100:0.5:2 with [ε-caprolactone] = 2 M at 25 °C after 30 min). The Al complexes bearing N,N′-diaryldithiooxalamidate demonstrated a greater catalytic activity (1.4–7.3-fold) than Al complexes bearing N,N′-diaryldioxalamidate. Density functional theory calculations revealed that [PhiPrNCS]2Al2(OMe)4with a weaker Al–OMe bond and less repulsion of the highest transition state TS1revealed the lower potential energy of TS1compared to [PhiPrNCO]2Al2(OMe)4and further exhibited a higher polymerization rate than [PhiPrNCO]2Al2(OMe)4.

In this study, aluminum complexes bearing ferrocene-based and arylthiomethylphenolate ligands were synthesized, and their catalytic activity for ε-caprolactone (CL) polymerization was investigated. The catalytic activity of the reduced form of Al complexes was higher than that of the oxidized form. The CL polymerization rate of the reduced form fcO2AlMe(75 min, conversion = 100%) was higher than that of the oxidized form fcoxO2AlMe(4320 min, conversion = 45%), and the CL polymerization rate of fc(OAlMe2)2(40 min, conversion = 100%) was higher than that of fcox(OAlMe2)2(60 min, conversion = 97%). Electron deficiency substituents on phenolate decreased the catalytic activity of Al complexes bearing arylthiomethylphenolate ligands. Density functional theory calculations revealed that thioether coordination stabilized the transition state (TS1) and that the oxidized form fcox(OAlMe2)2exhibited weaker thioether coordination and higher activation energy in TS1compared with those of the reduced form fcO2AlMe. In addition, our study determined that the thioether group is a suitable chelating group for Al catalysts in CL polymerization due to its labile nature.

Three titanium (Ti) compounds bearing 2,6‐bis(o‐hydroxyalkyl)pyridine ligands were synthesized, and used in vitro cytotoxicity against triple‐negative breast cancer (TNBC) MDA‐MB‐231 cells was studied. The results of in vitro cytotoxicity of the complexes against TNBC cells revealed that (HLMeTi‐O)4(IC50= 0.91 μM) exerted a significant inhibitory effect on the proliferation of TNBC cells. Thus, titanium alkoxide complexes as nonplatinum complex could be used for structural optimization for treating breast cancer cells in the future. Three titanium (Ti) compounds bearing 2,6‐bis(o‐hydroxyalkyl)pyridine ligands were synthesized, and used in vitro cytotoxicity against triple‐negative breast cancer (TNBC) MDA‐MB‐231 cells was studied. The results of in vitro cytotoxicity of the complexes against TNBC cells revealed that (HLMeTi‐O)4 (IC50 = 0.91 μM) exerted a significant inhibitory effect on the proliferation of TNBC cells.

This study compared ε‐caprolactone (CL), L‐lactide (LA), and ε‐decalactone (DL) polymerizations, where aluminum complexes bridged by two pyrazole ligands was used as catalysts. The reactivites of these Al complexes between CL, LA, and DL polymerization were different that LBu2Al2Me4, with the distort boat form, exhibits the greatest catalytic activity for LA and DL polymerization at 60°C but the lowest catalytic activity for CL polymerization at room temperature. This may be because dinuclear LBu2Al2Me4cannot react with BnOH to form aluminum benzyl oxide at room temperature, making it unable to reduce catalytic activity. Because these aluminum complexes had different reactivities for LA and CL polymerizations, the selectivity of polylactide‐gradual‐poly‐ε‐caprolactones (PLA(10–80%)‐gradual‐PCL(59–79%)) (PLA‐g‐PCLs) was observed. LBu2Al2Me4exhibits the greatest catalytic activity for L‐lactide and ε‐decalactone polymerizations at 60°C but the lowest catalytic activity for ε‐caprolactone polymerization at room temperature. This may be because LBu2Al2Me4cannot react with benzyl alcohol to form an active catalyst at room temperature, making it reduced catalytic activity. The synthesis of polylactide‐gradual‐poly‐ε‐caprolactone was investigated, and the copolymers (where the amount of polylactide varied from 10 to 80% and that of poly‐ε‐caprolactone varied from 59 to 79%) were produced.

A series of zinc complexes, [LXZnEt](1–5) and [LXZn2(OAc)3] (6–9), associated with NNO‐tridentate Schiff base ligands (2‐(((2‐((cyclohexyl[methyl]amino)methyl)phenyl)imino)methyl)phenolate (CAP) derivatives), were synthesized, and their activity toward ring‐opening polymerization (ROP) of L‐lactide (LA) and the reaction of CO2with cyclohexene oxide were also investigated. All of [LXZnEt]revealed excellent catalytic activity to ring‐opening polymerization (ROP) of LA in the presence of benzyl alcohol. Among them, [LHZnEt] (1)showed the highest activity with 82% conversation within 45 s. In contrast, [LXZn2(OAc)3] (6–9)were inactive in ROP of L‐lactide. In addition, all of these Zn complexes demonstrated moderate activity in the reaction of CO2with cyclohexene oxide in the presence of Bu4NCl. A series of Zn complexes associated Schiff base ligands were synthesized, and their applications in L‐lactide polymerization and the reaction of CO2with cyclohexene oxide were studied. Ethyl Zn complexes with electron donation group or steric bulky group on the phenyl ring revealed the low catalytic activity in L‐lactide polymerization..

A series of Cu complexes bearing N-heterocyclic carbene were synthesized, and their application for the copper-catalyzed azide–alkyne cycloaddition reaction was studied. The catalytic results demonstrated that [L2Cu]Br exhibited the most activity, and the trend of the other complexes was I > Br > Cl ∼ BF4> PF6. The 1H NMR spectrum of the reaction of LCuCl and phenylacetylene demonstrated that the NHC ligand dissociated from the Cu atom and deprotonated phenylacetylene to produce phenylacetylide. The conductivity study also proved this phenomenon. According to the density functional theory calculations, a mechanism was proposed in which acetylide copper halide was formed after NHC ligand dissociation and phenylacetylene deprotonation. Then, the six-membered metallacycle from the cycloadditions of methyl azide with mononuclear copper acetylide reacted with the second copper catalyst, (NHC)CuX, to form the dinuclear intermediate, which in turn underwent a rapid ring contraction to form another more stable dinuclear intermediate. After the protonation by neighboring NHC–H+, triazole was produced, and two (NHC)CuX catalysts were recovered.

The palladacycle complex [LsPdOAc]2bearing 2‐phenyl benzothiazole was synthesized and characterized by NMR and X‐ray crystallography. [LsPdOAc]2was used as a catalyst in the Suzuki–Miyaura cross coupling reaction of 4‐bromotoluene with phenylboronic acid, which resulted in a conversion of >90% with 5 mol% of the Pd complex within 10 min at 60°C. The palladacycle complex [LsPdOAc]2bearing 2‐phenyl benzothiazole was used as a catalyst in the Suzuki–Miyaura cross coupling reaction. In a case of 4‐bomotoluene and phenylboronic acid with Cs2CO3as a base in a 1:1 mixture solvent (3 mL) of DMF + H2O at 60 °C after 10 min, the conversion is 90 %.

A series of dinuclear aluminum (Al2Pyr2) complexes bridged by two pyrazole ligands were synthesized, and their catalytic activity toward ring-opening polymerization of ε-caprolactone (CL) was investigated. Different types of the Al–N–N–Al–N–N skeletal ring were found among these Al2Pyr2complexes. The butterfly form, LThio2Al2Me4, exerted the highest catalytic activity for CL polymerization. κ2-CL coordination with both Al centers within the butterfly form LThio2Al2Me4facilitates the initiation process. Generally speaking, the Al2Pyr2complexes exhibited substantially higher catalytic activity for CL polymerization than literature examples such as β-diketiminate- or traiaza-bearing aluminum complexes. In fact, the Al2Pyr2complexes can even carry out CL polymerization at room temperature.

β-Diketiminato copper(I) complexes play important roles in bioinspired catalytic chemistry and in applications to the materials industry. However, it has been observed that these complexes are very susceptible to disproportionation. Coordinating solvents or Lewis bases are typically used to prevent disproportionation and to block the coordination sites of the copper(I) center from further decomposition. Here, we incorporate this coordination protection directly into the molecule in order to increase the stability and reactivity of these complexes and to discover new copper(I) binding motifs. Here we describe the synthesis, structural characterization, and reactivity of a series of unsymmetrical N-aryl-N′-alkylpyridyl β-diketiminato copper(I) complexes and discuss the structures and reactivity of these complexes with respect to the length of the pyridyl arm. All of the aforementioned unsymmetrical ß-diketiminato copper(I) complexes bind CO reversibly and are stable to disproportionation. The binding ability of CO and the rate of pyridyl ligand decoordination of these copper(I) complexes are directly related to the competition between the degree of puckering of the chelate system and the steric demands of the N-aryl substituent.

In this study, a series of Al complexes bearing β-ketiminates and β-thioketiminates were synthesized and used as catalysts in ε-caprolactone (CL) polymerization. SPr–Alhad the highest catalytic activity among all Al complexes bearing β-thioketiminates and was more active than OPr–Al(2.8 times as high for CL polymerization) ([CL]/[SPr–Al]/[BnOH] = 100:1:2, [SPr–Al] = 0.02 M, conversion = 96% after 20 min at 25 °C). All Al complexes bearing β-thioketiminates exhibited higher catalytic activity (2.1- to 24.9-fold) relative to β-ketiminates. The polymerization results demonstrated that swapping oxygen atoms for sulfur atoms in β-ketiminate-associated Al complexes improved the catalytic activity of Al complexes for CL ROP.

Chondroitin sulfate-g-poly(ε-caprolactone) (CP) copolymers were synthesized via atom transfer radical addition (ATRA). The CP copolymers self-assembled into micelles in water, and the micelles could be used to encapsulate a hydrophobic anticancer drug, camptothecin (CPT), in the core for tumor targeting delivery. The physicochemical properties of the micelles and CPT-loaded micelles were thoroughly characterized. For the in vitro test, the CPT release, the protection of the lactone ring of CPT from hydrolysis and the cellular uptake of CPT were studied. The cell-killing and apoptosis-inducing effects using the CPT-loaded micelles were significantly better than using free CPT against CRL-5802 cells. The micellar internalization into CRL-5802 cells was primarily via CD44 and clathrin dual-mediated endocytosis. For the in vivo test, the therapeutic efficacy of the CPT-loaded micelles was studied in a non-small-cell lung cancer xenograft animal model. The CPT-loaded micelles showed good inhibition in tumor growth as compared with a commercial product, CPT-11, in CRL-5802 tumor-bearing mice. The in vitro and in vivo data suggested the CP-based micelles are promising anticancer drug vehicles for lung cancer targeting.

A new series of dinuclear zinc complexes of the types LZnEt2and LZn(-OBn)2(where L NNO-tridentate Schiff base ligand) have been prepared. The activities of zinc alkoxides, LZn(-OBn)2, toward the ring-opening polymerization of l-lactide have been investigated. Experimental results indicate that the reactivity of LZn(-OBn)2was dramatically affected by both the electronic and steric effect of the substituents on the Schiff base. The polymerization kinetics using L1Zn(-OBn)2(2a) as an initiator were also studied, and the experimental results reveal that the rate of reaction is first-order, which depends on both LA and L1Zn(-OBn)2. Furthermore, the heterotactic PLA with Prup to 91% can be achieved by initiating of L5Zn(-OBn)2in CH2Cl2at −55 °C.

Trinuclear aluminum complexes bearing bipyrazoles were synthesized, and their catalytic activity for ε-caprolactone (CL) polymerization was investigated. DBu2Al3Me5exhibited higher catalytic activity than did the dinuclear aluminum complex LBu2Al2Me4(16 times as high for CL polymerization; [CL]:[DBu2Al3Me5]:[BnOH] = 100:0.5:5, [DBu2Al3Me5] = 10 mM, conversion 93% after 18 min at room temperature). Density functional theory calculations revealed a polymerization mechanism in which CL first approached the central Al atom and then moved to an external Al. The coordinated CL ring was opened because the repulsion of two tert-butyl groups on the ligands pushed an alkoxide initiator on an external Al to initiate CL. In these trinuclear Al catalysts, the central Al plays a role in monomer capture and then collaborates with the external Al to activate CL, accelerating polymerization.

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