Β-diketone Derivatives Research Articles

Red/near-infrared (NIR) difluoroboron β-diketonate derivatives with reversible mechanochromism for cellular imaging

Near-infrared (NIR) fluorophores have promoted the development of materials for bioimaging, but traditional NIR dyes usually suffer from aggregation-caused quenching (ACQ), impeding their applications. Herein, we propose two difluoroboron β-diketonate complexes TBO and TBS, consisting a donor–acceptor (D-A) structure with triphenylamine (TPA) moiety as an electron donors and difluoroboron as well as furan or thiophene building block as an electron acceptor. The theoretical calculation and optical data shows that both of them have intramolecular charge transfer (ICT) characteristics. Such ICT characteristics endow them with both solvatochromism and dual-state emission (DSE) properties. In the solvent CH2Cl2, the emission wavelength of TBO ranges from 550 nm to 750 nm, with a low fluorescence quantum yield (Φ = 7.0 %). However, in the less polar solvent hexane, the emission wavelength blue-shifts, with an increased Φ reaching up to 18 %. Moreover, TBO and TBS exhibit mechanochromic characteristics and rare multi-channel fluorescence emission phenomena at solid-state. Their solid-state samples can emit fluorescence in four spectral bands with maximum emission wavelengths at 300 nm, 400 nm, 600 nm, and 770 nm under excitation at 240 nm. These unique optical properties are expected to be utilized for detecting polarity of system and deformation. Moreover, according to the results of cell imaging and flow cytometry, TBO molecular were easily internalized into Hela cells and distributed in the cytoplasm with strong red fluorescence. Therefore, this research inspires more insight into development of NIR luminogens for biomedical imaging.

Ruthenium(II) complexes of curcumin and β-diketone derivatives: effect of structural modifications on their cytotoxicity.

Ruthenium(II) complexes (Ru1-Ru3) with the general formula [Ru(O-O)(PPh3)2(bipy)]PF6, bearing two triphenylphosphine (PPh3), bipyridine (bipy) and a series of natural and synthetic β-diketones (O,O) ligands were synthesized and characterized using various analytical techniques. The interaction between the complexes and calf thymus DNA (CT-DNA) was investigated and demonstrated a weak interaction. The cytotoxicity of the complexes was investigated against breast cancer cells (MDA-MB-231 and MCF-7), lung cancer cells (A549), cisplatin-resistant ovarian cancer cells (A2780cis), as well as non-tumour lung (MRC-5) and non-tumour breast (MCF-10A) cell lines. All complexes exhibited cytotoxic activity against all the cell lines studied, with half maximal inhibitory concentration (IC50) values ranging from 0.39 to 13 µM. Notably, the three complexes demonstrated selectivity against the A2780cis cell line, with IC50 ranging from 0.39 to 0.82 µM. Among them, Ru2 exhibited the highest cytotoxicity, with an IC50 value of 0.39 µM. Consequently, this new class of complexes shows good selectivity towards cisplatin-resistant ovarian cancer cells and it is promising for further investigation as anti-cancer agents.

COMPUTER SIMULATION OF THE STRUCTURE OF SOME AZO-DERIVATIVES OF β-DIKETONES BY THE METHODS OF QUANTUM CHEMISTRY

The electronic and spatial structures of newly synthesized derivatives of β-diketones were studied based on the results of quantum chemical calculations. The properties of β-diketones with substituted phenyldiazonium chloride, namely 8 tautomers aryl derivatives of β-diketones-(E)-3-(2-(1-(dimethylamino)-1,3-dioxobutan-2-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzene sulfonic acid (H3L1) have been studied using the PM3 semi-empirical quantum chemistry method and the density functional theory (DFT) method with the B3LYP hybrid functional and 6-31+G(d,p) basis set. Energy and electronic characteristics of 8 tautomers are investigated. The effect of intramolecular hydrogen bonding on the structure of the investigated compounds has been studied. The formation of hydrogen bonds was confirmed by Natural Bond Orbital (NBO) analysis. Theoretical studies using the PM3 and DFT methods confirm the practical conclusions about the superiority of the hydrazone form in real samples.

Synthesis, Characterization, DFT, and In Silico Investigation of Two Newly Synthesized β-Diketone Derivatives as Potent COX-2 Inhibitors.

Despite extensive genetic and biochemical characterization, the molecular genetic basis underlying the biosynthesis of β-diketones remains largely unexplored. β-Diketones and their complexes find broad applications as biologically active compounds. In this study, in silico molecular docking results revealed that two β-diketone derivatives, namely 2-(2-(4-fluorophenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione and 5,5-dimethyl-2-(2-(2-(trifluoromethyl)phenyl)hydrazono)cyclohexane-1,3-dione, exhibit anti-COX-2 activities. However, recent docking results indicated that the relative anti-COX-2 activity of these two studied β-diketones was influenced by the employed docking programs. For improved design of COX-2 inhibitors from β-diketones, we conducted molecular dynamics simulations, density functional theory (DFT) calculations, Hirshfeld surface analysis, energy framework, and ADMET studies. The goal was to understand the interaction mechanisms and evaluate the inhibitory characteristics. The results indicate that 5,5-dimethyl-2-(2-(2-(trifluoromethyl)phenyl)hydrazono)cyclohexane-1,3-dione shows greater anti-COX-2 activity compared to 2-(2-(4-fluorophenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione.

An unique furan/thiophene substituted β-diketonate derivatives bearing triphenylamine with dual-state emission

Traditional β-diketones are rarely used as fluorescent emitters. Here, two novel triphenylamine-modified β-diketonate derivatives containing either a furan or thiophene unit (TPA-DK-O and TPA-DK-S) have been designed, synthesized and fully characterized. Both of the emitters have D-A type configuration, and show abnormal dual-state emissive characters with high quantum efficiency both in dissolved and aggregate state owning to rational design strategy. Additionally, owing to their molecular conformational flexibility and inherent intramolecular charge transfer characteristics, TPA-DK-O and TPA-DK-S show intriguing optical features such as solvatochromism, vicosity-dependent fluorescence and temperature response characteristics. The solvatochromism is derived from the intramolecular charge transfer effect which is confirmed by density functional theory calculation and fluorescence in solvents of different polarities. These unique optical properties of TPA-DK-O and TPA-DK-S are expected to be utilized for detecting local viscosity, polarity of system and temperature sensing. Moreover, the excellent dual-state emissive characters of TPA-DK-O are utilized for chemical sensors and cell imaging. The metal ion detection experiments indicated that TPA-DK-O has a fluorescence response capability to Fe3+ and Mg2+, and has a good linear relationship in the concentration range of 48–800 μM and 0–30 μM for Fe3+ and Mg2+, respectively. The cell incubation experiments shows that TPA-DK-O has low toxicity and good biocompatibility for cells. The cell imaging experiments reveals that TPA-DK-O not only stains and images cells, but also responds to Fe3+ in living cells. Making a contrast between TPA-DK-O and TPA-DK-S, it is found that replacing furan with thiophene in the β-diketonate derivatives showed slight effects on optical properties.

Bluish-green-to-green thermally activated delayed fluorescent emitters based on β-diketone derivatives exhibiting a horizontal emission dipole orientation ratio of 88% and an external quantum efficiency of nearly 25%

A series of β-diketone-based TADF emitters named MCzX derivatives are designed and prepared. Among these emitters, MCzDBM exhibits a PLQY of 79%, horizontal emission dipole orientation ratio of 88%, and high EQE of approximately 25%.

Synthesis and bacteriostatic properties of epoxybenzooxocino[4,3-b]pyridine derivatives

We report a successful chemical modification of (2,5-dimethyl-11,12-dihydro-5H-5,11-epoxybenzo[7,8]oxocino[4,3-b]pyridin-3-yl)ethan-1-one at C-3 position. The main synthetic procedures included the Claisen type condensation of oxocino[4,3-b]pyridinе with ethyl acetate. The obtained β-keto-enol derivative was further involved in cyclization with N,N- and N,O-binucleophiles forming corresponding heterocycles. Multicomponent reaction of synthesized β-diketone derivative with 2-nitroacetophenone in presence of urotropine and ammonium acetate led to the formation of 5-nitro-1,4-dihydropyridine derivative, oxidation of which provided the corresponding 5-nitropyridine. The reaction of oxocino[4,3-b]pyridine with hydroxylamine was also studied on a par with a reduction of acetyl group at C-3 position. ADMET and potential protein targets in Homo sapiens were predicted. Molecular docking was performed with proteins that can be structural parts of the M. tuberculosis and/or M. bovis. Antituberculosis and antibacterial activity of new compounds was investigated with preliminary biological assays.

Cyclometalated Platinum(II) Metallomesogens Based on Half-Disc-Shaped β-Diketonate Ligands with Hexacatenar: Crystal Structures, Mesophase Properties, and Semiconductor Devices.

A series of new half-disc-shaped platinum(II) complexes [Pt(ppy)(ALn-6OCnH2n+1)] (Pt-An), [Pt(ppyF)(ALn-6OCnH2n+1)] (Pt-Bn), and [Pt(ppyCF3)(ALn-6OCnH2n+1)] (Pt-Cn) (ALn-6OCnH2n+1 = 1,3-bis(3,4,5-trialkoxyphenyl)propane-1,3-dionato; n = 1, 6, 12) with concise structures have been designed and synthesized, in which 2-phenylpyridine (ppy) derivatives were used as cyclometalated ligands and hexacatenar β-diketonate derivatives ALn-6OCnH2n+1 as auxiliary ligands. The single-crystal data of the methoxy diketonate analogues Pt-A1, Pt-B1, and Pt-C1 indicate that they all display excellent square planarity. These platinum(II) complexes show a certain emission tunability (ranging from λ = 506-535 nm) by the introduction of fluorine or trifluoromethyl into ppy. Thermal studies reveal that the fluorine-substituted complexes are liquid crystals but the trifluoromethyl-substituted complexes are not. The platinum(II) complexes Pt-A12, Pt-B6, and Pt-B12 can form a hexagonal columnar mesophase via intermolecular π-π interactions. In addition, compared to the reported platinum(II) metallomesogens, Pt-A12 and Pt-B12 exhibit improved ambipolar carrier mobility behaviors in semiconductor devices at the liquid crystal states.

The Theoretical and Experimental Investigation of the Fluorinated Palladium β-Diketonate Derivatives: Structure and Physicochemical Properties.

To search for new suitable Pd precursors for MOCVD/ALD processes, the extended series of fluorinated palladium complexes [Pd(CH3CXCHCO(R))2] with β-diketone [tfa−1,1,1-trifluoro-2,4-pentanedionato (1); pfpa−5,5,6,6,6-pentafluoro-2,4-hexanedionato (3); hfba−5,5,6,6,7,7,7-heptafluoro-2,4-heptanedionato (5)] and β-iminoketone [i-tfa−1,1,1-trifluoro-2-imino-4-pentanonato (2); i-pfpa−5,5,6,6,6-pentafluoro-2-imino-4-hexanonato (4); i-hfba-5,5,6,6,7,7,7-heptafluoro-2-imino-4-heptanonato (6)] ligands were synthesized with 70–80% yields and characterized by a set of experimental (SXRD, XRD, IR, NMR spectroscopy, TG) and theoretical (DFT, Hirshfeld surface analysis) methods. Solutions of Pd β-diketonates contained both cis and trans isomers, while only trans isomers were detected in the solutions of Pd β-iminoketonates. The molecules 2–6 and new polymorphs of complexes 3 and 5 were arranged preferentially in stacks, and the distance between molecules in the stack generally increased with elongation of the fluorine chain in ligands. The H…F contacts were the main ones involved in the formation of packages of molecules 1–2, and C…F, F…F, NH…F contacts appeared in the structures of complexes 4–6. The stability of complexes and their polymorphs in the crystal phases were estimated from DFT calculations. The TG data showed that the volatility differences between Pd β-iminoketonates and Pd β-diketonates were minimized with the elongation of the fluorine chain in the ligands.

4,4,4-trifluoro-1-phenylbutane-1,3-dione metal [Cu(II) and Ni(II)] complexes as an superlative antibacterial agent against MRSA: Synthesis, structural quantum-chemical and molecular docking studies

• Copper and nickel complexes with β-diketone derivative were successfully synthesized and characterized. • Single crystals structures were confirmed by X-ray diffraction method and the coordinates were optimized with DFT calculations. • Antibacterial activities show that the complexes inhibit bacterial growth significantly in the presence of light compared to the absence of light. • Complexes showed very good binding affinity with FtsZ protein of MRSA. Infectious disease caused by multi-drug resistant (MDR) bacteria is a major problem in the present scenario due to the lack of treatment. In the present investigation, two β-diketone metal complexes {[Cu(TFPBD) 2 ]: complex 1 and Ni[(TFPBD) 2 (THF) 2 ]: complex 2} are synthesized using 4,4,4-trifluoro-1-phenylbutane-1,3-dione (TFPBD) ligand, and are characterized by FT-IR, TGA,UV-visible, SEM and EDX. Complexes 1 and 2 were structurally confirmed by single crystal X-ray analysis and are optimized using density functional theory. Slightly distorted square planar (complex 1) and octahedral (complex 2) geometry around the central metal ion is explored. Several intermolecular hydrogen bond and π-π interactions involved in the crystal packing were observed and are quantified by Hirshfeld surface analysis. The new metal complexes inhibited MRSA growth significantly and MIC of complexes are determined in the presence and absence of visible light. Complex 1 showed better MIC value compared to Complex 2. Copper complex reduced MRSA growth (5.3 to 0.1 Log CFU/mL) within 12 h and zone of inhibition at 12 µg/ml is 12 mm in presence of light. In this view, synthesized metal complexes are docked with FtsZ protein of MRSA using docking studies. FtsZ is an essential target for discovering new antibacterial compounds.

Polyaromatic ring containing β-diketone derivatives with antiproliferative activity toward human breast cancer cell lines: Synthesis, structure, DNA binding and molecular docking

The β-diketone derivatives in plants exhibit biological activity due to tautomerism and extended conjugation with the aromatic ring system. β-diketone derivatives; (Z)-3-(4-(4-aminophenoxy)phenylamino)-1,3-diphenylprop-2-en-1-one(L1) and (2Z,2′Z)-3,3′-(4,4′-oxybis(4,1-phenylene)bis(azanediyl)bis (1,3-diphenylprop-2-en-1-one(L2) were synthesized and characterized by spectral and single-crystal XRD analysis illustrate the compounds are in ketamine form. The study assessed the cytotoxicity and apoptotic effect of L1 and L2 and similar ketamines against human breast cancer (MCF 7) cell lines. The compounds showed selective inhibitory activity against the breast cancer cell lines. Interestingly, L1 and L2 bearing extended conjugation through –O linkage exhibit higher anticancer activity with inhibitory concentration values (IC50) comparable with the standard drug (Tamoxifen). Further investigations using DCFH-DA and DAPI staining assay revealed the compounds induce cell apoptosis by producing intracellular Reactive Oxygen Species (ROS). To further investigate, the binding attribute of L1-L4 with CT DNA was assessed, and the compounds were docked with DNA duplex of sequence, d(CGCGAATTCGCG)2 and breast cancer protease (3EU7).

Deep NIR-I Emissive Iridium(III) Complex Bearing D-A Ligand: Synthesis, Photophysical Properties and DFT/TDDFT Calculation

Near-infrared (NIR) phosphorescent iridium(III) complexes have been demonstrated to possess photophysical properties superior to those of traditional NIR dyes. However, the NIR emission wavelength is restricted in the range of 700–800 nm. For realizing deeper NIR emission, a novel type of iridium(III) complex was designed and synthesized in this work. The main ligand of the iridium(III) complex was constructed using a donor-acceptor structure containing benzothiophene as the donor and quinoxaline as the acceptor. The β-diketone derivative was chosen as the auxiliary ligand owing to its symmetrical structure and p-donating character. The complex exhibits deep NIR-I phosphorescence (764 nm in CH2Cl2, 811 nm in aqueous solution) and broad full width at half maximum (108 nm in CH2Cl2, 154 nm in aqueous solution). Theoretical calculations based on the density function and time-dependent density function were carried out to support the experimental data. Moreover, in vitro biological performance of the complex was determined as well. This work supports the possibility that via a systematic transformation between the D and A units, the photophysical performance of NIR emissive iridium(III) complexes can be greatly improved.

Separation and Recovery of Gold(III), Palladium(II) and Platinum(IV) by Solvent Extraction Using a New β-Diketone Derivative from Acidic Solutions.

This study indicates that a new amine derivative of β-diketone (EDAB-acac) can be successfully used in an acidic medium (HCl) to separate a mixture containing Au(III), Pd(II), and Pt(IV) ions using solvent extraction. The study was conducted in single and ternary model solutions. The impact of acid concentration and the type of solvent (toluene, chloroform, methylene chloride, 2-ethylhexanol) on separation efficiency was discussed. It has been shown that increasing the HCl concentration in the aqueous phase does not favor extraction. In contrast, solvents with high donor numbers (methylene chloride, 2-ethylhexanol) increase both the extraction percentage of Pd and Au as well as the separation coefficients of Pd in relation to Au and Pt. The palladium(II) and gold(III) (which form 4-coordinated planar [MCl4]2− complexes) are extracted most efficiently, Pd(II) (87–93%) and Au(III) (56–62%). The stripping of Au(III), Pd(II), and Pt(IV) ions from the EDAB-acac-methylene chloride phase was also investigated using 0.5 M ammonia aq., mineral acid (5 M HCl, 5 M HNO3), 0.1 M thiourea in HCl and 0.5 M ammonium thiocyanate. A 3-step stripping process was proposed for the recovery of Pd(II), Au(III), and Pt(IV) from the Pd-Au-Pt mixture in the EDAB-acac-methylene chloride system. In the first stage, the aqueous phase is treated with 5 M HNO3 (Pt separation), followed by the application of 0.5 M ammonia (Pd separation) and, finally, 0.1 M thiourea in HCl (Au separation). The solvent extraction with EDAB-acac in acidic medium (HCl) can be used for separation of Pd(II) and Au(III) ions from e-waste leach solutions.

The role played by structural and energy parameters of β-Diketones derivatives as antenna ligands in Eu(III) complexes

Structural and energy parameters role of six β-diketone antennas (symmetry, bulkiness, quenching bonds, donor groups and coordination) were analyzed. Six β-diketone derivatives and its complexes Eu(Phen)(X)3 and Gd(Phen)(X)3(X = β-diketone), were synthetized, characterized, experimentally studied through photophysical characterization. To analyze the contribution of each antenna to the photophysical properties, TD-DFT calculations were performed. To elucidate the antennas/Eu(III) energy levels involved in the energy transfer process CASSCF calculations were performed. Two antenna ligands effectively feed the europium center. A ligand without symmetry, with donor groups, without quenching bonds, and capable to fulfill the energy requirements, is the best antenna ligand for these complexes.

Thermodynamic study of volatile iridium (I) complexes with 1,5-cyclooctadiene and acetylacetonato derivatives: Effect of (O,O) and (O,N) coordination sites

Three hetero-ligand volatile iridium (I) complexes with β-diketonate derivatives [Ir(cod)(L)] (cod = 1,5-cyclooctadiene, L = CH3C(O)CHC(X)CH3, X = O (acac) 1, N–H (i-acac) 2, N–CH3 (Mei-acac) 3) have been synthesized, purified and characterized in order to investigate the influence of (O,O) and (O,N) coordination sites in chelate ligand on the thermochemical properties of this type compounds. β-Ketoiminate complexes (L = i-acac, Mei-acac) were prepared for the first time. Thermal behavior of iridium complexes in condensed phase has been studied by differential scanning calorimetry and thermodynamic parameters of melting processes (Δmelt.Hm.p., Δmelt.S°m.p.) have been determined for the first time. The temperature dependencies of saturated vapor pressures over the solid complexes have been measured by flow (transpiration) method (temperature intervals (363–423) K, (383–431) K and (383–420) K for compounds 1, 2 and 3, respectively). Using these data, the thermodynamic parameters of sublimation processes (ΔsubHT, ΔsubS°T) have been calculated. It has been found that although the ligand modification has a minor effect on the vaporization characteristics of this type complexes, the volatility unexpectedly decreases in the following sequence: L = acac > i-acac > Mei-acac. However, the vapor pressure values in the above-mentioned temperature interval are sufficient to all complexes studied be used as effective volatile precursors to obtain iridium-containing coatings by chemical vapor-phase deposition methods.

Extraction of lithium from wastewaters using a synergistic solvent extraction system consisting of Mextral EOL and Cyanex 923

A process-controlled synergistic solvent extraction (SSX) system consisting Mextral EOL (β-diketone derivative) and Cyanex 923 (mixture of four alkyl phosphine oxides) has been developed for the extraction of lithium from borate and sodium rich wastewaters induced by boron industry. In order to determine regression models and determine optimum conditions, a D-optimal experimental plan was created. Reduced cubic models were chosen for all lithium and sodium extraction studies. Accordingly, the most negative effect in lithium extraction was the aqueous phase/organic phase ratio (A/O), while the pH was the most positively effective parameter. Mextral EOL had no effect on sodium extraction. Notably, it was found that Mextral EOL and Cyanex 923 had up to 1.6 times synergistic effect on lithium extraction. In optimization, the sodium extraction efficiency is minimized while the lithium yield is maximized. Three different optimization criteria were determined in each wastewater and three different optimum alternatives were established. Accordingly, the highest lithium yield was predicted to be above 91.0% and sodium yield was below 4.70%. In back-extraction studies, water and different concentrations of HCl acid solutions were used as scrubbing and stripping agents. As a result, the Mextral EOL/Cyanex 923/Kerosene SSX system has been proven to be an effective method for maximizing lithium extraction from borate-rich wastewaters and for minimizing sodium extraction.

Influence of substituents on the reduction potential and pKa values of β-diketones tautomers: A theoretical study

Insight is provided into the reduction potential, pKa, energy of deprotonation and other electronic properties of eleven keto-enol tautomers of β-diketone derivatives, using density functional methods (DFT) and higher computational G3(MP2) methods. The computed reduction potential significantly reproduced the experimentally reported reduction potential values, with a mean absolute deviation (MAD) of 0.037 eV when using the higher computational G3(MP2) method, and a MAD of 0.061 eV when using the M06/6-311+G(df,p) DFT only method. Calculations proved a greater ease of reduction for the enol form of the β-diketones, indicated by higher (less negative) reduction potentials than their keto counterparts. The enol forms showed a further differentiation, with even higher reduction potentials observed when enolization occurred furthest from the more electron withdrawing side group. Latter enols also resulted in a lower dipole of the linking fragment between the electron donor and acceptor fragments (side groups). The computational results further provided more insight into the experimentally observed pKa values, suggesting the possibility of proceeding by deprotonation of the hydroxy group from the enol form of the molecules, rather than their keto form. The strength of the O⋯H hydrogen bonds in the enol forms of the β-diketones increased for the enolization site closest to the more electron withdrawing side group and proved to be stronger in the β-diketones with a higher experimental pKa. The computed hyperpolarizability of β-diketones was found to be highly dependent on the position of enolization, increasing with a lower band gap, higher polarizabilities (Δα1, Δα2) and lower stability or higher aromaticity, in terms of the exaltation index (Γ).

On/Off Fluorescent Chemosensor for Selective Detection of Divalent Iron and Copper Ions: Molecular Logic Operation and Protein Binding.

Here, naphthalene diamine-based β-diketone derivative (compound LH) was successfully used as a dual signaling probe for divalent cations, Fe2+ and Cu2+ ions, in bimodal methods (colorimetric and fluorometric). It showed fluorescent enhancement for Fe2+ ion by photoinduced electron transfer mechanism and fluorescence quenching for Cu2+ ion by charge-transfer process. Binding stoichiometry for [LH–(Fe2+)2] and [LH–(Cu2+)2] was found to be 1:2 by Job’s plot method and, the binding constants were calculated as 1.6638 × 1010 and 9.22929 × 108 M–1, respectively. Compound LH exhibited OR and XOR logic gate behavior with H+, Fe2+, and Cu2+ as inputs. Further, the compound LH and bovine serum albumin binding interaction showed quenching of fluorescence by Förster resonance energy-transfer mechanism.

β-Diketone derivatives: influence of the chelating group on the photophysical and mechanofluorochromic properties.

A diphenyl-boron β-diketonate complex was synthesized. Its photophysical properties were studied in solution and in the solid-state, and compared to those of its parent diketone and the corresponding difluoro-boron complex. TD-DFT calculations show that the molecular orbitals involved in the first Franck-Condon transition are very different for the three compounds studied. The difluoro-boron complex is strongly fluorescent in solution, and remains fluorescent in the solid-state. The free diketone turns to be very weakly fluorescent in solution and displays significant Aggregation Induced Enhanced Emission (AIEE) in the crystalline state, which can be explained by a rigidification of the molecule, while the diphenyl-boron complex is weakly fluorescent in solution as well as in the solid-state. For the free diketone and the difluoro-boron complex a mechanofluorochromic response is observed upon grinding the crystalline powder in a mortar, while for the diphenyl-boron complex no fluorescence emission change is detected under these conditions. Overall, this study shows that the nature of the chelating group has a crucial influence on the photophysical and mechanofluorochromic properties of β-diketonate complexes, leading to a wide variety of behaviors within the closely related structures of such derivatives.

Terbium Functionalized Micelle Nanoprobe for Ratiometric Fluorescence Detection of Anthrax Spore Biomarker.

Rapid, sensitive, and selective quantitative detection of pyridine dicarboxylic acid (DPA) as biomarker of anthrax spores is in great demand since anthrax spores are highly lethal to human beings and animals and also potential biological warfare agents. Herein, we prepared a ratiometric fluorescence lanthanide functionalized micelle nanoprobe by "one-pot" self-assembly, with an amphiphilic ligand containing β-diketone derivative which can "immobilize" terbium ions through the coordination interaction and a fluorophore as fluorescence reference (FR). The detection strategy was ascribed to Tb3+ ions in lanthanide functionalized micelle, which can be sensitized to emit the intrinsic luminescence upon addition of DPA due to the presence of energy transfer when DPA chromophore coordinated with Tb3+ ion. The fluorescence intensity of FR remained essentially constant, leading to ratiometric fluorescence response toward DPA. The results demonstrate that the terbium functionalized micelle was able to sensitively detect DPA with a linear relation in the range of 0 μM to 7.0 μM in aqueous solution, which also showed remarkable selectivity to DPA over other aromatic ligands. Our work paves a new way in the design of ratiometric fluorescence lanthanide functionalized micelle nanoprobes which can be promising for selective and sensitive detection of bacterial spores or biomolecules.