Cationic Units Research Articles

Porous Coordination Polymer Based on Bipyridinium Carboxylate Linkers with High and Reversible Ammonia Uptake.

The zwitterionic bipyridinium carboxylate ligand 1,1'-bis(4-carboxyphenyl)-4,4'-bipyridinium (pc1) in the presence of cadmium chloride affords novel porous coordination polymers (PCPs): [Cd4(pc1)3Cl6]·CdCl4·guest (1) crystallizing in the P3̅1c space group. In the structure, [Cd4Cl6(CO2)6] building units are linked together by six pc1 ligands, leading to a 3D high-symmetrical network exhibiting hexagonal channels along the c axis. The walls of this PCP consist of cationic electron-acceptor bipyridinium units. The PCP 1 reversibly adsorbs H2O and CH3OH up to about 0.1 g/g at saturation showing the adsorption isotherms characteristic of a moderately hydrophilic sorbent. Adsorption of ammonia (NH3) follows a different pattern, reaching an exceptional uptake of 0.39 g/g (22.3 mmol/g) after the first adsorption cycle. Although the crystalline structure of 1 collapses after the first adsorption, the solid can be regenerated and maintains the capacity of 0.29 g/g (17 mmol/g) in the following cycles. We found that the high NH3 uptake is due to a combination of pore filling taking place below 150 h·Pa and chemisorption occurring at higher pressures. The latter process was shown to involve two phenomena: (i) coordination of NH3 molecules to Cd(2+) cations as follows from (113)Cd NMR and (ii) strong donor-acceptor interactions between NH3 molecules and pc1 ligands.

Precise control of surface electrostatic forces on polymer brush layers with opposite charges for resistance to protein adsorption.

Various molecular interaction forces are generated during protein adsorption process on material surfaces. Thus, it is necessary to control them to suppress protein adsorption and the subsequent cell and tissue responses. A series of binary copolymer brush layers were prepared via surface-initiated atom transfer radical polymerization, by mixing the cationic monomer unit and anionic monomer unit randomly in various ratios. Surface characterization revealed that the constructed copolymer brush layers exhibited an uniform super-hydrophilic nature and different surface potentials. The strength of the electrostatic interaction forces operating on these mixed-charge copolymer brush surfaces was evaluated quantitatively using force-versus-distance (f-d) curve measurements by atomic force microscopy (AFM) and probes modified by negatively charged carboxyl groups or positively charged amino groups. The electrostatic interaction forces were determined based on the charge ratios of the copolymer brush layers. Notably, the surface containing equivalent cationic/anionic monomer units hardly interacted with both the charged groups. Furthermore, the protein adsorption force and the protein adsorption mass on these surfaces were examined by AFM f-d curve measurement and surface plasmon resonance measurement, respectively. To clarify the influence of the electrostatic interaction on the protein adsorption behavior on the surface, three kinds of proteins having negative, positive, and relatively neutral net charges under physiological conditions were used in this study. We quantitatively demonstrated that the amount of adsorbed proteins on the surfaces would have a strong correlation with the strength of surface-protein interaction forces, and that the strength of surface-protein interaction forces would be determined from the combination between the properties of the electrostatic interaction forces on the surfaces and the charge properties of the proteins. Especially, the copolymer brush surface composed of equivalent cationic/anionic monomer units exhibited no significant interaction forces, and dramatically suppressed the adsorption of proteins regardless of their charge properties. We conclude that the established methodology could elucidate relationship between the protein adsorption behavior and molecular interaction, especially the electrostatic interaction forces, and demonstrated that the suppression of the electrostatic interactions with the ionic functional groups would be important for the development of new polymeric biomaterials with a high repellency of protein adsorption.

Vibrational and structural properties of barbiturate anions in supramolecular compounds

In this work we have been successful in the synthesis, spectroscopic and structural characterization of five new supramolecular compounds of formulation [Ni(4dbpy2)2(H2O)2]Bb2·4H2O (1), [Mn(4dbpy2)2(H2O)2]Bb2·4H2O (2), [Mn(5dbpy2)2ClH2O][(C4O3N2H2)2-OH]·H2O (3), [Co(5dbpy2) (H2O)4]Bb2·2H2O (4) and [6dbpy2H] [(C4O3N2H2)2-OH]·H2O (5) which have been obtained from barbituric acid (HB) and 2,2′-bipyridine (4,4′, 5,5′ and 6,6′-dimethyl) building block ligands and transition metal ions, where Bb is the barbiturate monoanion and dbpy is the neutral substituted bipyridyl in the formulation. Compounds 1 and 2 are isomorphous, presenting the cationic block [M(4dbpy2)2(H2O)2]2+ neutralized by two uncoordinated barbiturate anions, whilst for compound 4 the different cationic units [Co(5dbpy2) (H2O)4]2+ are neutralized by the same anion. For the compounds 3 and 5 the formation of a new building block is recognized and characterized as the hydroxyhydurilate anion which has been generated in situ from the oxidation reaction between alloxan and the barbiturate anion. The Raman spectral analysis clearly shows the similarity of compounds 1 and 2 through similar wavenumber positions of all the vibrational bands, especially the band at 679cm−1 assigned to the ring breathing mode of the barbiturate anion which is present in compounds 1, 2 and 4. For compounds 3 and 5 the absence of this Raman band suggests that a noteworthy chemical modification has taken place in this building block and the appearance of a new band at 1745cm−1, assigned to the ν(CO) mode of the new hydroxyhydurilate anion generated in situ, supports this conclusion.

Calix [4]-bis-monothiacrown-5 as a versatile building block for homo- and heterometallic coordination polymers

Exocoordination-based homonuclear and heteronuclear coordination polymers of calix [4]-bis-monothiacrown-5 (L) are reported. L reacts with HgCl2 and affords a one-dimensional (1D) coordination polymer [L(μ-Hg2Cl4)]n (1) linked by neutral square-type Hg2Cl4 clusters. A straightforward one-pot reaction of L with a mixture of HgCl2 and KCl resulted in the isolation of a heteronuclear species [(K2L)(μ-Hg3Cl8)]n (2) adopting a 1D polymeric structure in which the endocyclic dipotassium(I) complex cation units of L are linked by anionic open double-square type (μ-Hg3Cl8)2− clusters. Both products form a pseudo 3D framework via interchain H-bonds and their topological analyses were also carried out.

Insight into the interactive effects of β-glycerophosphate molecules on thermosensitive chitosan-based hydrogels

The purpose of the present study was to provide insights into the interactive effects of β-glycerophosphate (β-GP) molecules on thermosensitive chitosan-based hydrogels, which experience sol–gel transformation around the physiological temperature. This study also investigated the influence of β-GP as a physical cross-linker and pH modifier on chitosan-based hydrogels by Fourier transform infrared spectroscopy with the aim of achieving a better understanding of the effect of β-GP action mechanism. For this purpose, some solutions with 2% (w/v) chitosan were mixed with different amounts of β-GP in the range of 0–20% (w/v) concentrations. It was shown that by further addition of β-GP, the anionic phosphate units of β-GP in combination with the cationic amine units of chitosan could provide electrostatic cross-linking for making chitosan-based hydrogels. All the β-GP–chitosan solutions remained at the physiological pH after complete mixing. In addition, the viability of 3T3 fibroblast cells determined by MTT assay and scanning suggested that the samples containing 12% β-GP would show optimum biological characteristics. This study demonstrated that the synthesized chitosan–β-GP is a biocompatible thermosensitive system, which can be potentially used for tissue engineering applications in different areas, such as cartilage injections, and that injectability and appropriate gelation behavior are important factors.

Bis-methyl imidazolium methylidene bis(trifluoromethanesulfonyl)imide, crystal structure, thermal and dielectric studies

A new geminal di-cationic ionic liquid (IL) containing a central cationic unit methylidene capped by a basic functionality (imidazole) is synthesized. The compound was characterized by means of1H,13C,19F NMR, IR and Raman spectroscopies and its crystal structure is confirmed by single crystal X-ray diffraction method. The X-ray studies on ([M(CH2)IM2+][2NTf\(_{2}^{-}\)]) show that it crystallizes in monoclinic system with space group: P 21/c. Thermal properties were investigated in the temperature range from 0 to 400∘C by using differential thermal (DTA) and thermogravimetric (TGA) analyses. The frequency-dependent electrical data are discussed using complex dielectric permittivity in the frequency range of (10−2–106 Hz) and in the temperature range of −50∘ to 20∘C. The outstanding dielectric and thermal properties make this IL as promising candidate for electrochemical devices.

Crystal structure and antimicrobial properties of tetrakis(imidazole)copper(II) triiodide, [Cu(imidazole)4](I3)2

ABSTRACTA new copper(II) complex of imidazole (Imz), [Cu(Imidazole)4](I3)2 (1), was prepared and its structure was determined by X-ray crystallography. The structure of [Cu(Imidazole)4](I3)2 (1) is ionic and consists of [Cu(Imidazole)4]2+ cationic units, and triiodide counter ions. In 1, the copper atom is bound to four nitrogen atoms of Imz and assumes a nearly regular square planar geometry. Antimicrobial activities of 1 and three other complexes were evaluated by minimum inhibitory concentration and the results showed that the complexes exhibited significant activities against gram-negative bacteria (E. coli, P. aeruginosa).

Di-μ-dimethylformamide-κ4O:O-μ-tetrahydrofuran-κ2O:O-bis[(tetrahydrofuran-κO)sodium(I)] bis(μ-3,6-dichlorobenzene-1,2-dithiolato-κ3S,S′:S)bis[(3,6-dichlorobenzene-1,2-dithiolato-κ2S,S′)iron(III)

The title compound, [Na2(C3H7NO)2(C4H8O)5][Fe2(C6H2Cl2S2)4], was synthesized and its crystal structure was solved. The ionic crystal contains a [Fe2(S2C6H2Cl2)4]2−dimeric anion and a [Na2(THF)4(μ-THF)(μ-DMF)2]2+cation, where THF is tetrahydrofuran and DMF is dimethylformamide, comprising two sodium atoms joined by one THF and two DMF molecules bridging through their O atoms. The five-coordinate environment of each Na site is completed by two terminal THF molecules. The asymmetric unit contains half a cationic unit (as the cation is placed on a twofold axis) and half an anion, as there is an inversion centre at the midpoint of the Fe—Fe vectors. The cationic and anionic moieties are linked by C—H...Cl and C—H...S interactions.

Reversible Vesicle–Spherical Micelle Transition in a Polyion Complex Micellar System Induced by Changing the Mixing Ratio of Copolymer Components

The mixing ratio dependence of the morphology of a polyion complex micelle formed of an anionic–neutral double-hydrophilic block copolymer (AP) and a cationic–neutral double-hydrophilic block copolymer (MP) in 0.1 M aqueous NaCl solution was investigated by using small-angle X-ray scattering (SAXS), electrophoretic light scattering (ELS), and isothermal titration calorimetry (ITC), under the condition that the anionic and cationic block chains are much longer than the neutral block chains. When the anionic and cationic monomer units in the solution are nearly equimolar, the net charge of the polyion complex micelle is close to zero, and the bilayer vesicle is formed. However, when the anionic or cationic monomer units in the solution are richer than the other, the polyion complex micelle is charged by including the excess block copolymer component to form the smaller spherical micelle. The morphology transition between the vesicle and spherical micelle can take place reversibly by simply adding AP or MP i...

Ionization basis for activation of enzymes soluble in ionic liquids

BackgroundThe complex interactions between electrolytes and proteins have been studied for more than a century. However, understanding is not yet complete and does not provide a basis for predicting the activity of enzymes in ionic media. The use of ionic liquids (ILs) as reaction medium has opened up new opportunities for better understanding of the mechanism of enzymatic catalysis. Although a number of properties of ILs have been correlated with enzyme function, these relationships are not completely understood at a molecular level. MethodsWe propose that ILs must be able to promote ionization of protein ionizable groups in order to dissolve active enzymes. The biocompatible IL need to possess a functional group with large donor number and acceptor number in both cationic and anionic units, each of which is based on a high dielectric constant lead structure. We designed and synthesized two series of ILs and determined their ionizing–dissociating abilities and activities of lipases soluble in these new ILs. ResultsThe results showed that the ionizing–dissociating abilities of ILs paralleled the catalytic activity trend of lipases dissolved in the ILs. The activities of lipases soluble in the newly designed ILs were comparable to those in water. ConclusionsWe can conclude that ionizing–dissociating abilities of an IL can be used as a basis for predicting the activity of enzymes soluble in the IL.General significanceIonization basis for activation of enzymes gives a deeper understanding of the behavior of enzymes in non-aqueous media at a molecular level.

Metal Complexes of Multitopic, Third Generation Poly(pyrazolyl)methane Ligands: Multiple Coordination Arrangements

The structures of metal complexes of two classes of multitopic, “third generation” poly(pyrazolyl)methane ligands, ligands specifically functionalized at the non‐coordinating “back” position, are discussed. For tris(pyrazolyl)methane based [(pz)3C–CH2–O–CH2]nC6H6–n (n = 2, 3, 4 and 6, pz = pyrazolyl ring) ligands, three bonding modes are observed depending on the metal, counterion and solvent: a) the κ3 (tripodal) mode, where all three pyrazolyl rings are coordinated to one metal; b) the κ2‐κ0 mode, with only two pyrazolyl rings bonded to a metallic center while the third is not involved in a donor bond; and c) in a κ2‐κ1 fashion, in which the tris(pyrazolyl)methane unit acts as a bridge between two metals. For bis(pyrazolyl)methane based [CH2–O–CH2–CH(pz)2]nC6H6–n ligands, the main structural arrangement is a mononuclear cationic unit in which two arms of the ligand bond a single silver(I) cation in a tetradentate fashion, giving rise to 16‐ or 17‐member metallacyclic structures.

Highly selective charge-guided ion transport through a hybrid membrane consisting of anionic graphene oxide and cationic hydroxide nanosheet superlattice units

The development of graphene-based functional membranes with the ability to effectively filter and separate molecules or ions in solutions based on a simple criterion (for example, the size or charge of solutes) is crucial for various engineering-relevant applications, ranging from wastewater purification and reuse to chemical refinement. Here, we report a hybrid membrane consisting of anionic graphene oxide (GO) and cationic Co-Al (or Mg-Al) layered double hydroxide (LDH) nanosheet (NS) superlattice units for high selectivity charge-guided ion transport. The hybrid membrane possesses a series of characteristics, including being easy to access, mechanically robust, freestanding, flexible and semitransparent as well as having a large area. The interlayer spacing of the hybrid membrane is insensitive to humidity variations, ensuring the structural stability in solution-based mass transport applications. The concentration gradient-driven ion transmembrane diffusion experiments show that the cations bearing various valences can be effectively separated strictly according to their charges, independent of the cationic and charge-balancing anionic species. The relative selectivity of the hybrid membranes toward monovalent and trivalent cations is as high as 30, which is not achievable by GO multilayer stacks, LDH-NS multilayer stacks or their bulk-stratified membranes, indicating that a synergistic effect originating from the molecular-level heteroassembly of GO and LDH-NS has a dominant role in the high-performance charge-guided ion filtration and separation processes. These excellent properties of GO/LDH-NS hybrid membranes make them promising candidates in diverse applications, ranging from wastewater treatment and reuse and chemical refinement to biomimetic selective ion transport. A membrane that combines ultrathin carbon films with metallic nanosheets may find use in wastewater treatment and biomimetic ion transport. Graphene oxide is a promising two-dimensional building block for purification technology because it naturally stacks into thin layers on solution processing. By tailoring the interlayer spacing with different functional groups, researchers can create nanochannels that permit water to flow while rejecting molecules above a certain size. Now, Hongwei Zhu of Tsinghua University in Beijing and co-workers have expanded the capabilities of such membranes by sandwiching minerals known as layered double hydroxides (LDHs) into the graphene oxide framework. The cationic metals within LDH nanosheets helped the membrane selectively filter impurities with different charge levels — for example, particles with triple positive charges were rejected at a ratio of 30:1 relative to singly charge ions. We demonstrate our recent progress in the newly emerging and intriguing research field of developing graphene-based functional membranes with the ability to effectively filtrate and separate molecules or ions in solutions based on a simple criterion (for example, the size or charge of solutes) for various engineering-relevant applications ranging from wastewater purification and reuse to chemical refinement.

How Does the Solvent Modulate Shuttling in a Pillararene/Imidazolium [2]Rotaxane? Insights from Free Energy Calculations

Pillararene-based [2]rotaxanes have gained notoriety since the synthesis of the first pillar[5]arene in 2008. The marked propensity of pillararenes to bind cationic groups is often utilized to prepare functional host–guest complexes. Interestingly enough, the interaction of pillararenes with cationic groups is modulated by the nature of the solvent. The molecular mechanism that underlies binding, examined experimentally, remains, however, partially understood. In the present contribution, the solvent-controlled motion in a [2]rotaxane composed of a 1,4-diethoxypillar[5]arene (P[5]) ring threaded onto an hydrogen-bond donor imidazolium axle was investigated in eight different solvents. Apart from the polarity, the hydrogen-bond-accepting ability of the solvent was considered with particular care. In environments featuring hydrogen-bond acceptors, the P[5] tends to include the alkyl chain at one end of the axle, staying away from the cationic imidazolium unit at the other end of it. Inclusion is primarily d...

Secondary Structures in Inorganic Helicates of an Octadentate Phenanthroline‐Type Schiff Base Ligand

AbstractTo analyze the contribution of supramolecular interactions to helical architectures and to investigate whether ligand folding can be induced by only protons in a similar fashion in the absence of metal ions, a new 1,10‐phenanthroline (phen)‐based extended ligand, C12H6N2[CHNC6H4NH(C10H6N)]2 (L1), its copper(I) complexes, [Cu2(C12H6N2{CHNC6H4NH(C10H6N)}2)2] [PF6]2 (1), [Cu2(C12H6N2{CHNC6H4NH(C10H6N)}2)2][BF4]2 (2), [Cu2(C12H6N2{CHNC6H4NH(C10H6N)}2)2][CuCl2]2·CH2Cl2 (3), and [Cu4(C12H6N2{CHNC6H4NH(C10H6N)}2)2][Cu2I4] (4), were prepared and structurally characterized. Ligand L1 wraps copper(I) ions in two intriguingly different fashions depending on the nature of the anions. Although dicopper helicates 1–3 and tetracopper helicate 4 show significant intermolecular interactions that show considerable structural relationships with DNA, helicate 4 more closely resembles the structural features of DNA that even phen‐based stacking interactions are present between the two helical strands. In complex 4, the dinuclear [Cu2I4]2– dianion is involved in intermolecular interactions, which joins two cationic units in a linear fashion, whereas the monoanions in complexes 1–3 (i.e., PF6–, BF4–, and CuCl2–) are only involved in intramolecular interactions or connect the cations laterally. The anion‐dependent topology serves as a reminder that the helical topology of a cation can be altered by changing the nature of the anion.

Diblock Polyelectrolytic Copolymers Containing Cationic Iron and Cobalt Sandwich Complexes: Living ROMP Synthesis and Redox Properties.

Diblock metallopolymer polyelectrolytes containing the two redox-robust cationic sandwich units [CoCp'Cp](+) and [FeCp'(η(6)-C6 Me6)](+) (Cp = η(5)-C5 H5; Cp' = η(5)-C5H4-) as hexafluorophosphate ([PF6](-)) salts are synthesized by ring-opening metathesis polymerization using Grubbs' third generation catalyst. Their electrochemical properties show full chemical and electrochemical reversibilities allowing fine determination of the copolymer molecular weight using Bard-Anson's electrochemical method by cyclic voltammetry.

Some Pb(II) complexes of 2, 6-bis (Hydroxymethyl) Pyridine with different Pb(II) Salts involving the anions chloride, Perchlorate and Nitrate. A Photoelectron spectroscopic study

Some Pb(II) complexes of 2, 6-bis(hydroxymethyl)pyridine (dhmp) with different Pb(II) salts [PbCl2.6H2O, Pb(ClO4)2.6H2O, Pb(NO3)2.3H2O] are synthesized and characterized and studied by IR, NMR and mass spectroscopy. The distortion of the coordination polyhedron, dependent on the anion kind influence on the distribution of donor sites and the formation of mononuclear complexes. There is no case the contortions of Pb(II) salt or water of hydration were found in the coordination sphere. Spectroscopy data shows that complexes are mononuclear 2: 1 (L: M) complexes. The ligand dhmp components is mono-deprotonated and act as anionic ligand. The complex number 4 show same behavior. But in 1, 2 and 4 complexes it behave as neutral ligand. The basal planes are occupied by O donors and N atoms are in the axial positions of Octahedral in 3 and 4 the basis are formed by two O and two N donor atoms, and O atoms are in the axes. Complex 3 shows the N atoms in trans position but 4 shows N atoms in cis position. Complexes (1–4) shows packing and cationic complex unit is strong and weak hydrogen bond interactions involving the contortions and hydroxyl hydrogen atoms or aromatic hydrogen atoms to stabilize the complexes.

Supermolecular assembly of polyoxoanion and metal–organic cationic units towards a model for core–shell nanostructures

Two novel core–shell-like molecular composites [NiL3]4[HVIV12VV6O42(PO4)] and [NiL2]4[HVIV12VV6O42(PO4)] were designed and synthesized, which exhibited electrocatalytic activity for the reduction of H2O2 and oxidation of NO2−.

Assembly of polyoxometalates and Ni-bpy cationic units into the molecular core–shell structures as bifunctional electrocatalysts

Four core–shell organic–inorganic hybrid materials composed of polyoxometalates and Ni-bpy units were designed and synthesized, which exhibited bifunctional electrocatalytic activity for the reduction of NO2− and water oxidation.

Syntheses and characterization of various supramolecular compounds from the self-assembly of nickel(II) hexaaza macrocyclic complex with carboxylic acid derivatives

The supramolecular compounds [Ni(C16H38N6)(2,7-NDC)] (1), [Ni(C16H38N6)(H2O)2] [Ni(C16H38N6)(1,3,5-BTC)2] (2), and [Ni(C16H38N6)(nicotinate)2] (3) were prepared via self-assembly of a nickel(II) azamacrocyclic complex containing butyl pendant groups, [Ni(C16H38N6)(ClO4)2], with 2,7-naphthalenedicarboxylic acid (2,7-NDC), 1,3,5-benzenetricarboxylic acid (1,3,5-BTC), and nicotinic acid, respectively. These compounds were characterized by elemental analysis, infrared spectroscopy, magnetic measurement and single crystal X-ray diffraction. In 1, the nickel(II) azamacrocyclic complex links two 2,7-NDC2− ligand at the axial position and each 2,7-NDC2− ligand binds two adjacent nickel(II) azamacrocylic units with syn–syn and syn–anti orientations to form a zigzag 1-D chain structure. The zigzag 1-D chain tends to interact via offset face-to-face π–π interactions with adjacent 1-D chains, which leads to a 2-D supramolecular network. Compound 1 exhibits very weak antiferromagnetic interactions through the bridged 2,7-NDC2− ligand within the 1-D zigzag chains (g=2.11 and J/κB=−0.29cm−1). Compound 2 consists of two nickel(II) azamacrocyclic cation units and one nickel(II) azamacrocylic anion unit. Each nickel(II) ion in the cation and anion units is coordinated with four nitrogen atoms of the azamacrocyclic ligand in the equatorial plane, and two oxygen atoms from the water molecules or BTC3− ligands at the axial positions, to display a distorted octahedral geometry. The cation and anion units form intermolecular hydrogen bonds, giving rise to a 3-D supramolecular structure. In 3, the coordination environment around the nickel(II) ion has a distorted octahedral geometry via coordination with four nitrogen atoms of the azamacrocyclic ligand in the equatorial plane, and two nicotinate anions at the axial positions and intramolecular hydrogen bonding interactions between the amine groups and nicotinate anions stabilize the molecular structure.

Mitochondria-Targeted Near-Infrared Fluorescent Off-On Probe for Selective Detection of Cysteine in Living Cells and in Vivo.

Cysteine (Cys) plays crucial roles in biological systems and in mitochondrial processes. Highly selective probes for specific detection of mitochondrial Cys over other biological thiols are rare. Herein, we designed and synthesized a mitochondria-targetable near-infrared (NIR) fluorescent off-on probe, NFL1, based on a fluorescein derivative for Cys detection. Probe NFL1 has a lipophilic cation unit as the mitochondria biomarker and an acrylate group as the Cys-recognition unit as well as a fluorescence quencher. The probe itself is nonfluorescent due to the photoinduced electron transfer process. Upon addition of Cys, marked enhancement in the NIR emission (735 nm) can be monitored due to cleavage of the acrylate moiety. This probe had great sensitivity and selectivity for the rapid detection of Cys over homocysteine (Hcy) and glutathione (GSH) with an ultralow detection limit of 14.5 nM. More importantly, the probe successfully targeted mitochondria, detected endogenous Cys, and assessed mitochondrial oxidative stress in living cells. Probe NFL1 was also capable of detecting and imaging Cys in living nude mice, indicating its significant potential in biological applications.