Laser spectroscopy imaging technique coupled withnanomaterials for cancer diagnosis: A review

Laser spectroscopic imaging techniques have received tremendous attention in the-eld of cancer diagnosis due to their high sensitivity,high temporal resolution,and short acquisition time.However,the limited tissue penetration of the laser is still a challenge for the in vivo diagnosis of deep-seated lesions.Nanomaterials have been universally integrated with spectroscopic imaging techniques for deeper cancer diagnosis in vivo.The components,morphology,and sizes of nanomaterials are delicately designed,which could realize cancer diagnosis in vivo or in situ.Considering the enhanced signal emitting from the nanomaterials,we emphasized their combination with spectroscopic imaging techniques for cancer diagnosis,like the surface-enhanced Raman scattering(SERS),photoacoustic,fluorescence,and laser-induced breakdown spectroscopy(LIBS).Applications ofthe above spectroscopic techniques offer new prospectsfor cancer diagnosis.

Preface to special column on catalytic conversion of CO_(2)

With the increasing awareness of sustainable chemistry and green chemistry,catalytic conversion of carbon dioxide(CO_(2))into high value‐added and bulk chemicals is a promising tech‐nology that can utilize CO_(2) as an ideal C1 source while simulta‐neously storing renewable energy.Despite being frustrated with its thermodynamic stability and kinetic inertness,CO_(2) has been tamed for triggering catalytic constructions of highly‐valued entities like important hydrocarbon fuels and fine chemicals,mainly aiding by two scenarios:CO_(2) reduction and CO_(2)‐involved organic synthesis.Accordingly,science,industry and govern‐ment agencies have been devoted to leverage these synthetic tools in targeting the catalytic conversion of CO_(2).Therefore,it motivates us to organize the special column of“Catalytic Con‐version of CO_(2)”.The column contains 14 papers,including 4 reviews,4 communications and 6 articles,which cover the frontiers and most of the research aspects of catalytic con‐version of CO_(2).

Preparation and Characterization of Low Density Poly(Imino Imino Ketone)Foam

Poly（Imino Ketone） （PIK） is a group of novel high performance polymer material with excellent thermal properties and dissolubility. Aiming at the requirements of inertial confined fusion （ICF） studies on low density polymer foams, we firstly synthesized poly（imino imino ketone） （PIIK） by palladium catalyzed C-N cross-coupling reaction, and successfully prepared the PIIK foam material with a density of 80-300 mg/cm3 by using PIIK as the raw material with thermal-induced phase separation and lyophilization technique. Mercury injection method was used to determine the structure of PIIK foams, and the results indicated that the mean pore diameter was lower than 5 ~tm and it had relatively high voidage and specific surface area.

Regioselective and asymmetric allylic alkylation of vinyl epoxides for the construction of allylic alcohols via synergistic catalysis

A highly efficient asymmetric allylic alkylation of cyclic and acyclic carbon nucleophiles with vinyl epoxides has been developed,which exhibits good functional group compatibility,high atomic and step economy.This protocol utilizes a strategy of synergistic catalysis with a chiral N,N'-dioxide/Ni~Ⅱ complex and an achiral Pd~0 catalyst,generating a series of multisubstituted allylic alcohols with a quaternary carbon stereocenter in high yield and excellent regio-,Z/E-and enantioselectivity under mild conditions.Further transformations of the product demonstrate the potential utility of this protocol in the synthesis of allyl alcohol derivatives and natural product analogues.Experimental studies revealed that the N,N′-dioxide/metal complexes play an important role in controlling the Z/E-and enantioselectivity.The density functional theory(DFT) calculations further demonstrated that multiple C–H···π interactions between the aromatic rings of the two substrates and the amide moiety in the ligand stabilized the dominant transition state.

Photocatalytic dicarboxylation of strained C-C bonds with CO_(2) via consecutive visible-light-induced electron transfer

Dicarboxylic acids have a wide range of applications in the polymer industry to construct valuable materials.Photocatalysis has recently emerged as an efficient and sustainable strategy to generate dicarboxylic acids.However,photocatalytic dicarboxylation with CO_(2) is mainly limited to unsaturated bonds,and the dicarboxylation of C-C single bonds still remains a challenge.Herein,we report a photocatalytic dicarboxylation of C-C single bonds in strained rings with CO_(2) units via consecutive photo-induced electron transfer(ConPET).It is also the first photocatalytic reductive ring-opening reaction of cyclobutanes.Notably,this transition-metal-free protocol exhibits good functional group tolerance,broad substrate scope,facile scalability,and easy product derivatizations.Moreover,diacids can easily be derivatized to mainchain liquid crystalline polyesters.

Pd catalysts supported on modified Zr_(0.5)Al_(0.5)O_(1.75) used for lean-burn natural gas vehicles exhaust purification

Composite supports Zr0.5Al0.5O1.75 modified by metal oxides, such as La2O3, ZnO, Y2O3 or BaO, were prepared by co-precipitation method, and palladium catalysts supported on the modified composite supports were prepared by impregnation method. Their properties were characterized by X-ray diffraction （XRD）, NH3 temperature-programmed desorption （NH3-TPD）, He temperature-programmed reduction （He-TPR）, N2 adsorption/desorption, and CO-chemisorption. The catalytic activity and the resistance to water poisoning of the prepared Pd catalysts were tested in a simulated exhaust gas from lean-burn natural gas vehicles with and without water vapor. The results demonstrated that the modified supports had an apparent effect on the performance of Pd catalysts, compared with the Pd catalyst supported on the unmodified ZrA1. The addition of ZnO or Y203 promoted the conversion of CH4. In the absence of water vapor, Pd/ZnZrA1 exhibited the best activity for CH4 conversion with the light-off temperature （Tso） of 275 ℃ and the complete conversion temperature （T90） of 314 ℃, respectively. However, in the presence of water vapor, Pd/YZrA1 was the best one over which the light-off temperature （Tso） of methane was 339 ℃ and the complete conversion temperature （T90） was 371 ℃. These results indicated that Pd catalyst supported on the modified composite ZrA1 support showed excellent catalytic activity at low temperature and high resistance to H20 poisoning for the exhaust purification of lean-burn natural gas vehicles.

C–H alkylation of pyridines with olefins catalyzed by imidazolin-2-iminato-ligated rare-earth alkyl complexes

An array of rare-earth bis(aminobenzyl)complexes supported by imidazolin-2-iminato ligands were synthesized and structurally characterized.These complexes showed high activity towards ortho-Csp^(2)–H alkylation of 2-alkylpyridines and benzylic Csp^(3)–H alkylation of 2,6-dialkylpyridines with alkenes.A wide range of alkyl or aryl substituted olefin substrates are compatible,providing an atom-economical route to linear or branched alkylated pyridine derivatives in moderate to high yields(45 examples,up to 99%yield).The primary study suggested that the asymmetric version of Csp^(3)–H alkylation of 2,4,6-collidine with allylbenzene was feasible with chiral imidazolin-2-iminato-ligated scandium(III)complexes,and good yield with moderate enantioselectivity was obtained(84%yield,84:16 er).Mechanistic investigations including kinetic isotope effect(KIE)experiments and density functional theory(DFT)calculations shed light on the catalytic cycle and the origin of enantiocontrol.

Construction of Angularly Fused Tricyclic Compounds via Photo-induced Radical Cascade Cyclization

Photo-induced electron transfer (PET) of silyl enol ethers has been employed to synthesize several fused ring systems. However, the method has limited applicability due to its narrow substrate scope, low product yields, unsatisfactory stereo- and regioselectivity. Herein, we report a PET-triggered cascade reaction of silyl enolates that leads to the formation of angularly fused tricyclic scaffolds. The reaction exhibits broad substrate scope and excellent stereoselectivity. The regio- and stereoselectivity of this cascade reaction is elucidated via DFT calculation and conformational analysis.

Chiral nickel(Ⅱ) complex catalyzed asymmetric(3+2) cycloaddition ofα-diazo pyrazoleamides with 2-siloxy-1-alkenes

A highly efficient asymmetric(3 + 2) cycloaddition of α-diazo pyrazoleamides with silyl enol ethers was realized by employing a chiral N,N’-dioxide-Ni(II) complex catalyst. The process includes the formation of chiral nickel carbenoid intermediate and the following enantioselective cycloaddition reaction. The desired dihydrofuran O,O-acetal derivatives were obtained in good yields(up to 90%) with high enantioselectivity(up to 99% ee) under mild reaction conditions within short reaction time. On the basis of the determination of the catalyst structure, a possible transition state mode was proposed.

Asymmetric annulations based on cycloisomerization of cyclopropyl tethered allenyl ketones by bimetallic relay catalysis

The diastereo-and enantioselective tandem cycloisomerization/[4+2]-cycloaddition reaction of cyclopropyl tethered allenyl ketones withα,β-unsaturated carbonyl compounds was realized firstly under mild reaction conditions by using bimetallic silver(I)/chiral metal-N,N′-dioxide catalysts,providing a facile and atom-economic route to enantioenriched polysubstituted furopyran derivatives with good results.Possible transition state models were proposed to explain the stereoinduction.

New chiral N-heterocyclic olefin bifunctional organocatalysis inα-functionalization ofβ-ketoesters

N-heterocyclic olefins(NHOs)possess an electron-rich and highly polarized C=C double bond due to the donating property of nitrogen atoms.This feature imparts exocyclic carbon atom of NHOs with strong basicity and high nucleophilicity.Although NHOs have been emerging as a new type of organocatalyst and ligand for metal complexes in organic synthesis,chiral NHOmediated highly enantioselective organic transformations were still elusive.Herein,we developed a new type of chiral aminederived C_(2)-symmetric NHOs and employed them as efficient chiral bifunctional organocatalysts for asymmetricα-functionalization ofβ-ketoesters.With as low as 0.1 mol%catalyst loading,the desired amination and trifluoromethylthiolation products were afforded in good yields with high enantioselectivities(up to 99%yield and 99%ee).Experimental studies and theoretical calculation disclosed that hydrogen-bonding interaction upon protonation and other weak interaction between substrate and catalyst were crucial for the enantiocontrol.

Asymmetric catalytic alkylation of vinyl azides with 3-bromo oxindoles: water-assisted chemo-and enantiocontrol

A highly chemo-and enantioselective alkylation of vinyl azides with 3-bromo-3-substituted oxindoles was achieved through a chiral N,N′-dioxide/Ni(OTf)2-mediated conjugate addition/water addition/elimination tandem process. Water was critical to the chemo-and enantioselectivity. The hydrated Na3PO4 acted as both a base and a reservoir to regulate the amount of water in solution. A wide range of enantioenriched oxindoles having α-carbonyl-substituted all-carbon quaternary stereocenters were achieved in good yields and good ee values(51 examples, up to 90% yield, 97% ee). Easy transformations of products to analogues of(+)-physovenine and(+)-desoxyeseroline enhanced the synthetic value. Mechanistic studies including control experiments, kinetic studies, and density functional theory(DFT) calculations, enabled a proposition of a possible catalytic cycle along with transition states to elucidate the reaction process and chiral induction.

Enantioselective synthesis of tetrasubstituted allenes via addition/arylation tandem reaction of 2-activated 1,3-enynes

We report the development of a new class of multifunctional chiral guanidine/Pd(0)catalyst system for 1,4-addition/arylation tandem reaction.A variety of tetra-substituted allenes were readily accessible from three-component“one-pot”transformations of acyclic or cyclic 2-activated 1,3-enynes,malonates and halobenzenes under mild reaction conditions.High levels of yield and enantioselectivity were achieved in the construction of stereogenic center and axis using readily available acyclic guanidineamides.The mechanistic studies suggest that the guanidine/Pd(0)collaboration has obvious synergism to both base-dominated conjugate addition,and Pd(0)-dominated Heck-type reaction.

Regio-and enantioselective conjugate addition ofβ-nitroα,β-unsaturated carbonyls to construct 3-alkenyl disubstituted oxindoles

Reversal of regioselectivity in the catalytic asymmetric conjugate additions of 3-substituted oxindoles toβ-nitroenones orβ-nitroacrylates was established with chiral scandium catalysts.It enabled the construction of functionalized 3,3-disubstituted oxindoles,including terminal and internal vinyl groups in excellent yields and ee values.

Effects of thermal treatment conditions on redox properties of ceriazirconia materials

The nanostructures and redox properties of CeO_(2)-ZrO_(2)materials can be tuned via optimized thermal treatments.In this study,the CeO_(2)-ZrO_(2)-Y_(2)O_(3)-La_(2)O_(3)(CZ) materials were prepared by co-precipitation method and submitted to different thermal treatment conditions(atmosphere:nitrogen(N) and air(A);temperature(x):700,800 and 900℃).Due to the protective effects of the "in-situ-formed" carbon powder,treating the surfactants assisted-CZ precursors under N2atmosphere can keep the pore structures and then the CZ-N700 and CZ-N800 can achieve larger surface area than CZ-A700 and CZ-A800,respectively.In comparison,with high treatment temperature(900℃),the effects of thermal atmosphere on surface area can be ignored.However,the redox properties of CZ materials correlate closely with thermal treatment atmosphere and temperature simultaneously.As demonstrated by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) characterizations,the N_(2)atmosphere facilitates the formation of Ce^(3+)without disturbing the mixing degree of Ce and Zr.Thereby the CZ-Nx materials exhibit superior reducibility than corresponding CZ-Ax materials.In additio n,the XRD and XPS results also demonstrate the formation of a more homogeneous CZ solid solution by Zr atoms rearrangement with temperature ignoring the atmosphere.As a result,the reducibility of CZ materials increases with the treatment temperature increasing and is not affected by the worsening of the textural properties.Specially,due to the synergistic effects of N_(2)atmosphere and high treatment temperature,the CZ-N900 shows the best reducibility.This improvement also emphasizes the important role of structural properties of CZ in explaining the temperature-dependent reducibility.

Visible-light-driven thio-carboxylation of alkynes with CO_(2):facile synthesis of thiochromones

Difunctionalizing carboxylation of alkynes with CO_(2)is a sustainable and important strategy to generate valuable acrylate derivatives from both readily available starting materials.Such protocols,however,always suffer from the use of excess metallic reagents and transition metal residue.Herein,we report the first thio-carboxylation of alkynes with thiophenols and CO_(2),which is a visible-light-driven and transition metal-free process.In contrast to previous carboxylations of alkynes via two-electron activation of CO_(2),mechanistic and computational investigations suggest that the single-electron activation of CO_(2)is involved in the thio-carboxylation,rendering uniqueβ-carboxylation.The following cyclizing acylation affords important thiochromones efficiently.Moreover,the one-pot method features mild reaction conditions(room temperature,1 atmosphere of CO_(2)),high chemo-and regio-selectivity,easy scalability and facile derivatization of products to bioactive compounds.

Effect of loading content of copper oxides on performance of Mn-Cu mixed oxide catalysts for catalytic combustion of benzene

A series of Mn-Cu mixed oxide catalysts were prepared by precipitation method. The catalysts were characterized by N2 adsorp- tion-desorption, H2-TPR and XPS. When the loading ratio of manganese oxides to copper oxides was 8：2 or 7：3, the catalysts possessed better catalytic activity, and benzene was converted completely at 558 K. Results of H2-TPR showed that the loading of a small amount of copper oxides decreased the reduction temperature of catalysts. Results of XPS showed that the loading of a small amount of copper oxides increased the proportion of manganese and defective oxygen on the surface of catalysts, and stabilized manganese at higher oxidation state. And the catalyst with the loading ratio 7：3 was a little worse than 8：2, since the interaction between manganese oxides and copper oxides is too strong, copper oxides migrate to the surface of catalysts and manganese oxides in excess are immerged.

Synthesis of neodymium modified CeO_2-ZrO_2-Al_2O_3 support materials and their application in Pd-only three-way catalysts

Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The Pd-only three-way catalysts （Pd-TWC） supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3＋ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.

Visible-light-mediated external-reductant-free reductive cross coupling of benzylammonium salts with(hetero)aryl nitriles

Herein we report a novel visible-light-mediated external reductant-free reductive cross coupling for the construction of C sp2–C sp3 bonds.A variety of benzylammonium salts underwent selective coupling with(hetero)aryl nitriles to deliver important diarylmethanes under mild reaction conditions.Importantly,photocatalysts can be omitted for many cases,which might involve the electron donor acceptor(EDA)complex.Mechanistic studies indicated benzylic radicals might be involved as the key intermediates.Moreover,the in situ generated NMe3 via cleavage of C–N bond in ammonium salts acts as the electron donor,thus avoiding the use of external-reductant.

Prediction of Multicomponent Reaction Yields Using Machine Learning

Prediction of reaction yields using machine learning(ML)can help chemists select high-yielding reactions and provide prior experience before wet-lab experimenting to improve efficiency.However,the exploration of a multicomponent organic reaction features many complex variables and limited number of experimental data,which are challenging for the application of ML.Herein,we perform yield prediction for the synthesis of 2-oxazolidones via Cu-catalyzed radical-type oxy-alkylation of allylamines and herteroaryl-methylamines with CO_(2),which is a three-component reaction.Using physicochemical descriptors as features to launch ML modelling,we find that XGBoost shows significantly improved performance over linear models and these features are effective for the yield prediction.Moreover,out-of-sample prediction indicates the application potential of the model.This study demonstrates great potential of regression-modelling-based ML in organic synthesis even with complex factors and a general small size of reaction data,which are generated from the classical research pattern of method for the inquiry of multicomponent reactions.