Design and Construction of the Uranyl Coordination Polymer with Multifunction Stimulus Response: Fluorescent Sensors for Halide Ions and Photochromism.

It can provide ideas for the use of uranium elements in the treatment of spent fuel from nuclear wastewater to explore the application potential of uranium element. Thus, it is necessary to research the structure and properties of a novel uranyl coordination polymer (CP) for uranium recovery and reuse. Herein, we designed and prepared a new uranyl CP U-CMNDI based on UO22+ and H2CMNDI (H2CMNDI = N, N'-bis(carboxymethyl)-1,4,5,8-naphthalenediimide). Structural analysis shows that two uranyl ions are connected by two parallel deprotonated CMNDI ligands to form a discrete uranyl dimer structure. U-CMNDI can act as a potential stimulus-responsive halide ion sensor by a fluorescence "turn on" response in water. The limit of detection for fluoride (F-), bromide (Br-), iodide (I-), and chloride (Cl-) is 5.00, 5.32, 5.49, and 5.73 µM, respectively. The fluorescence "turn on" behavior is based on the photoinduced electron transfer (PET) mechanism between halide ions and electron-deficient NDI cores. In addition, U-CMNDI demonstrates a color response to ultraviolet light, exhibiting reversible photochromic behavior with a notable color change. The color change mechanism can contribute to the PET process and the radical process.

Stimulus-Responsive Lanthanide MOF Materials Encapsulated with Viologen Derivatives: Characterization, Photophysical Properties and Sensing on Nitrophenols.

Viologens (1,1'-disubstituted 4,4'-bipyridyls) possessing electron-deficient properties and redox activity are a class of suitable chromophores to assemble metal-organic hybrid photochromic materials. Thus, viologen-functionalized metal-organic frameworks (MOFs) have attracted much attention for their photochromic properties; however, the syntheses of lanthanide-viologen hybrid crystalline photochromic materials still face many challenges. For example, the structures and properties of the final products are difficult to predict and are limited by molecular configurations. In this work, host-guest composite-material Ln-NH2 BDC-pbpy MOFs were constructed by encapsulating viologen derivative pbpyCl2 . The pbpy2+ moieties are uniformly embed by their π-π conjugation in the pores of the 3D structure by electrostatic interactions. Due to the encapsulation of the chromophore pbpy2+ moieties, Ln-NH2 BDC-pbpy MOFs have reversible photochromic properties: they can change color after irradiation and can return to the original color after being protected from light or heating. Interestingly, the fluorescence intensity decreases with illumination time and recovers in the dark. As a result, Ln-NH2 BDC-pbpy MOFs show both photochromic and photomodulated fluorescence. Based on the outstanding fluorescence performance of the Ln-NH2 BDC-pbpy MOFs, they also show a wonderful effect for detecting nitrophenols, especially TNP.

Switchable Multiplex Photoelectrochemical Immunoassay of Aß42 and Aß40 Based on a pH-Responsive i-Motif Probe and Pyrene-Based MOF Photocathode.

In accurately diagnosing Alzheimer's disease (AD) and distinguishing AD from other dementia, the concentration ratio of amyloid-beta 42 (Aß42) to Aß40 is more reliable than the concentration of Aß42 alone. For the multiplex PEC assay, generating an independent photocurrent of multiple targets on a single interface is a great challenge. Herein, an i-motif-based switchable sensing approach is proposed to construct a pH-regulated multiplex PEC immunosensor for Aß42 and Aß40 by using Bi-TBAPy as an efficient photoactive cathode material. An independent photocurrent signal of Aß42 and Aß40 is produced through the regulation of the electron-transfer tunneling distance by a pH-dependent configuration transition of the i-motif DNA. In a 96-well plate, immunological recognition of Aß42 (or Aß40) coupled with an enzymatic catalytic reaction produces an acidic (or alkaline) lysis solution, which triggers the formation and unravelment of the i-motif structure. The above configuration transition regulates the distance between Au NPs labeled SH-DNA and Bi-TBAPy, leading to PEC signal switching. Smart integration of the pH-responsive switchable DNA probe with a high-efficiency photocathode enables the precise monitoring of Aß42 and Aß40 at a single interface in a wide detection range (10 fg/mL ∼ 1 µg/mL and 1 pg/mL ∼ 1 µg/mL) with detection limit of 4.5 fg/mL and 0.52 pg/mL, respectively. The proposed i-motif-based switchable sensing strategy paves a new avenue for a multiplex PEC assay on a single interface, showing great prospects in bioanalysis and early disease diagnosis.

Cage Bismuth Metal-Organic Framework Materials Based on a Flexible Triazine-Polycarboxylic Acid: Subgram Synthesis, Application for Sensing, and White Light Tuning.

Bismuth-based metal-organic frameworks (MOFs) have always attracted the attention of many researchers. Here, we first report a crystalline Bi-MOF (Bi-TDPAT) based on a flexible triazine-polycarboxylic linker 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine (H6TDPAT) and bismuth nitrate; its crystallite quality is adequately good and the diffraction data can be collected directly by single crystal X-ray diffraction rather than 3D electron diffraction. The structure of Bi-TDPAT belongs to a novel topology type btt. Notably, the synthesis scale of Bi-TDPAT can be expanded, and sub-gram synthesis can be realized. At the same time, we synthesized a microcrystalline material Bi-TATAB utilizing 2,4,6-tris(4-carboxylphenylamino)-1,3,5-triazine (H3TATAB). The structures of the two materials were characterized by several microanalysis tools. Considering that Bi-TDPAT is a blue light-emitting material with a broad emission peak, we prepared a white light emitting composite material Eu/Tb@Bi-TDPAT by encapsulating Eu(III)/Tb(III) in Bi-TDPAT. In addition, the fluorescence sensing functions of Bi-TDPAT and Bi-TATAB were explored. The results showed that they could detect and recognize various nitrophenols, and the optimal limit of detection is as low as 0.21 µM, which can be reused even after five cycles. Energy competitive absorption (CA) and photo-induced electron transfer are the main sensing mechanisms. By comparing and analyzing the properties of these two bismuth-based crystalline materials, we believe that this work also provides inspiration for the synthesis and development of bismuth-based MOF in the future.

Stimuli-Responsive Naphthalenediimide Cd-MOFs Tuned by Different Aliphatic Dicarboxylic Acids with Extended Spacers.

A series of novel Cd metal-organic frameworks (MOFs) (1-9) with different extended spacers with seven kinds of the aliphatic dicarboxylic acids as secondary building linkers based on N,N'-di(4-pyridylacylamino)-1,4,5,8-naphthalenediimide (NDI-A) have been designed and synthesized by changing the volume ratio of solvents under solvothermal conditions. In addition, the secondary building linkers of aliphatic dicarboxylic acids have different spacer lengths, resulting in different structures of complexes 1-9. So, their packing structures are affected by the degree of distortion of the NDI-A ligand, the different aliphatic dicarboxylic acids ligands, and the hydrogen-bonding patterns. Complexes 1-9 showed stimuli-responsive emission tuned by different aliphatic dicarboxylic acids with extended length spacers under UV light irradiation, accompanied by the color change from light orange to dark brown, and achieved reversible photochromic under heating, which indicates that they could serve as secret erasable inks. Moreover, complexes 1-9 exhibited selective vaporchromic behavior to methylamine (MA), and the vaporchromic sample could be recovered after washing with MeOH. It is worth noting that the preparation of poly(vinyl alcohol) (PVA)-NDI-MOF films enables the photochromic and vaporchromic properties of complexes 1-9 to apply in practice. In addition, complexes 1-9 exhibited good fluorescence properties as sensing probes toward 2,4,6-trinitrophenol (TNP) with lower limits of detection. In short, this work provides a broad field to explore the creative NDI-MOF materials with photoactive and luminescent properties.

Integrated Photoresponsive Alkaline Earth Metal Coordination Networks: Synthesis, Topology, Photochromism and Photoluminescence Investigation.

Photoresponsive materials are a key part of the age of smart technology that have potential in a broad range of applications. Coordination networks (CNs) are widely used due to their designability and stability. In this work, three novel alkaline earth metal coordination networks (AEM-CNs): [Mg(CMNDI)(H2 O)2 ], [Ca(CMNDI)(H2 O)2 ]⋅H2 O, and [Sr(CMNDI)(H2 O)(DMF)] with fsl, cds, and scn topology nets were synthetized via N,N'-bis(carboxymethyl)-1,4,5,8-naphthalenediimide (H2 CMNDI); the scn net is not found in the Reticular Chemistry Structure Resource or ToposPro. The reusable and sensitive photochromic properties of the three CNs enable them to be used as secret inks or ultraviolet detectors. In addition, the CNs also exhibited reusable photoluminescent turn-off toward the drug molecules, balsalazide disodium (Bal.) and colchicine (Col.), with good limits of detection of 0.16 and 0.70 µM. To the best of our knowledge, this is the first study of a fluorescence sensor for Bal. Thus, the AEM-CNs provide a design idea for integrated photoresponsive materials that could be further improved in the near future by further study.

Thorium-Organic Framework Constructed with a Semirigid Triazine Hexacarboxylic Acid Ligand: Unique Structure with Thorium Oxide Wheel Clusters and Iodine Adsorption Behavior.

We successfully prepared and characterized a distinctive thorium-based MOF (metal-organic framework) Th-TTHA with thorium oxide wheel clusters under the conditions of solvothermal synthesis by utilizing thorium nitrate and semirigid triazine hexacarboxylic acid linker H6TTHA (H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid). To the best of our knowledge, Th-TTHA is the first thorium-based MOF assembled by semirigid triazine hexapod ligand H6TTHA. It is worth mentioning that Th-TTHA exhibits a novel and distinctive arrangement of structure and topology. Th-TTHA has abundant adsorption sites such as the triazine ring that is rich in nitrogen atoms, N of NH-, and carboxyl oxygen atoms without coordination with a central metal, which drove us to explore its iodine adsorption capacity. The experimental results show that Th-TTHA shows excellent adsorption capacity for iodine, and the adsorption amount in a saturated iodine cyclohexane solution can reach 528 mg/g within 24 h. This work is greatly significant for the development of new structures of thorium-based MOFs and the expansion of its functional characteristics, which is very essential for our in-depth understanding of thorium chemistry and in the management and disposal of radionuclides and application of the nuclear fuel cycle.

Polyiodine-Modified 1,3,5-Benzenetricarboxylic Acid Framework Zn(II)/Cd(II) Complexes as Highly Selective Fluorescence Sensors for Thiamine Hydrochloride, NACs, and Fe3+/Zn2.

Four new complexes, [Zn(TIBTC)(DMA)]·[NH2(CH3)2] (1), [Cd(TIBTC)(H2O)]·[NH2(CH3)2]·DMA (2), [Cd2(TIBTC)(2,2'-bipy)2(HCOO)] (3), and [Cd2(DIBTC)(2,2'-bipy)2(HCOO)] (4) (H3TIBTC = 2,4,6-triiodo-1,3,5-benzenetricarboxylic acid, H3DIBTC = 2,4-diiodo-1,3,5-benzenetricarboxylic acid, 2,2'-bipy = 2,2'-bipyridine, and DMA = dimethylacetamide), were successfully synthesized and characterized by elemental analysis, powder X-ray diffraction, infrared spectroscopy, ultraviolet-visible spectroscopy, and thermogravimetric analysis. Complexes 1 and 2 are three-dimensional supramolecular network structures, while complex 4 has a two-dimensional network structure. We preliminarily studied the fluorescence properties of the complexes and found that complexes 1-3 can detect thiamine hydrochloride, NACs, and Fe3+/Zn2+ with high sensitivity and selectivity.

A Uranyl-Organic Framework Featuring Two-Dimensional Graphene-like Layered Topology for Efficient Iodine and Dyes Capture.

A novel uranyl-organic framework [(CH3)2NH2][UO2(TATAB)]·2DMF·4H2O (U-TATAB) was assembled through the solvothermal synthesis of UO2(CH3COO)2·2H2O and triazine tricarboxylate linker H3TATAB (H3TATAB = 4,4',4″-s-triazine-1,3,5-triyltri- p-aminobenzoate). It was characterized by single-crystal X-ray diffraction, elemental analysis, IR, powder X-ray diffraction, and thermogravimetric microanalysis. It is worth mentioning that U-TATAB exhibits an original arrangement of structures with interesting topology. Structural analysis confirmed that U-TATAB displays an interesting two-dimensional graphene-like layered topology. In order to broaden its functional characteristics, we first investigated the functional adsorbent U-TATAB for iodine capture in cyclohexane solution and for the removal of dye in aqueous solution. Large porosity, unique structure character, and the π-electron walls made of TATAB make the material a promising functional absorbent exhibiting excellent adsorption performance for iodine and dye molecules. Most notably, this is the first case of a uranyl-organic framework built by secondary building unit (SBU) [UO2(RCOO)3]- and extended trigonal triazine tricarboxylate ligand H3TATAB with amino functional groups.

Stable Lanthanide-Organic Framework Materials Constructed by a Triazolyl Carboxylate Ligand: Multifunction Detection and White Luminescence Tuning.

Under hydrothermal conditions, we have successfully synthesized six isostructural lanthanide coordination polymers, [LnL1.5(H2O)2]·1.75H2O (1-6; Ln = Eu, La, Pr, Nd, Sm, Gd), by the reaction of 5-methyl-1-(4-carboxylphenyl)-1 H-1,2,3-triazole-4-carboxylic acid (H2L) and Ln(NO3)3·6H2O. Structural analysis shows that polymers 1-6 show novel three-dimensional supramolecular network structures. The luminescent properties for polymer 1 have been investigated at room temperature. The results have shown that polymer 1 can be used as a chemical sensor for multifunctional testing such as UO22+, Fe3+ ion detection, and small organic molecule detection because of its strong fluorescence properties. In particular, polymer 1 exhibits extremely high selectivity and sensitivity for the detection of Fe3+ ions. In addition, white-light emission is achieved through a reasonable tuning proportion by mixing Gd3+ and Eu3+.

Multifunctional uranyl hybrid materials: structural diversities as a function of pH, luminescence with potential nitrobenzene sensing, and photoelectric behavior as p-type semiconductors.

A series of uranyl-organic frameworks (UOFs), {[(UO2)2(H2TTHA)(H2O)]·4,4'-bipy·2H2O}n (1), {[(UO2)3(TTHA)(H2O)3]}n (2), and {[(UO2)5(TTHA) (HTTHA)(H2O)3]·H3O}n (3), have been obtained by the hydrothermal reaction of uranyl acetate with a flexible hexapodal ligand (1,3,5-triazine-2,4,6-triamine hexaacetic acid, H6TTHA). These compounds exhibited three distinct 3D self-assembly architectures as a function of pH by single-crystal structural analysis, although the used ligand was the same in each reaction. Surprisingly, all of the coordination modes of the H6TTHA ligand in this work are first discovered. Furthermore, the photoluminescent results showed that these compounds displayed high-sensitivity luminescent sensing functions for nitrobenzene. Additionally, the surface photovoltage spectroscopy and electric-field-induced surface photovoltage spectroscopy showed that compounds 1-3 could behave as p-type semiconductors.

Near-IR Broadband-Absorbing trans-Bisphosphine Pt(II) Bisacetylide Complexes: Preparation and Study of the Photophysics.

Broadband near-IR absorbing trans-bis(trialkylphosphine) Pt(II) bisacetylide binuclear complex (Pt-1) was prepared with boron-dipyrromethene (Bodipy) and styrylBodipy acetylide ligands. Pt-1 shows strong absorption bands at 731 and 503 nm. Singlet energy transfer (EnT) and efficient intersystem crossing of the central coordinated Bodipy ligand were proposed to be responsible for the efficient funneling of the excitation energy to the triplet-state manifold. Reference complexes containing only a single Bodipy ligand were prepared for comparison (with styrylBodipy ligand Pt-0 or Bodipy ligand Pt-2). The molecular structures were confirmed by single-crystal X-ray diffraction. The photophysical properties were studied with steady-state and time-resolved transient absorption spectroscopies, electrochemical characterization, and density functional theory/time-dependent density functional theory calculations. Dual fluorescence was observed for Pt-1. Singlet EnT in Pt-1 was proposed based on the fluorescence quenching/excitation spectra, and femtosecond transient absorption spectra (energy transfer rate constant kEnT = 2.2 × 10(10) s(-1)). With nanosecond transient absorption spectra, intramolecular triplet-state energy transfer in Pt-1 was proved. Gibbs free energy changes of charge separation indicate that the photoinduced intramolecular electron transfer in Pt-1 is thermodynamically prohibited. Intermolecular triplet transfer between Pt-2 and L-1 was studied with nanosecond transient absorption spectra; the EnT rate and energy transfer efficiency were determined as 3.6 × 10(4) s(-1) and 94.5%, respectively. The singlet oxygen ((1)O2) photosensitizing of Pt-1 was improved as compared to the complexes containing only a single visible-light-absorbing chromophore.

Multiple Stimulus Response Material Based on Sr-tcbpe MOF for Mechanochromism, Visualization Labeling, and Etching Toward TNP.

The abuse and excessive discharge of organic pollutants such as nitroaromatic compounds (NACs) have become a hot topic of concern for all humanity and society, and the development of fast, effective, and targeted technical means for detecting NACs also faces many challenges. Here, we reported a strontium-based metal-organic framework (MOF) {[Sr2(tcbpe)(H2O)4]}n (Sr-tcbpe), in which tcbpe represents deprotonated 4',4‴,4″‴,4‴‴-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1'biphenyl]-4-carboxylic acid)). In Sr-tcbpe, Sr-O polyhedron and deprotonated tcbpe4- ligand have a staggered connection to form a self-assembled three-dimensional network structure. In addition, it is found that Sr-tcbpe undergoes no luminescent color change when grinding under solvent protection, while mechanochromic fluorescence behavior is observed when grinding directly, leading to luminescent color changes from cyan to green (Sr-tcbpe-G). Additionally, Sr-tcbpe and Sr-tcbpe-G could selectively detect PNP, DNP, and TNP, and Sr-tcbpe achieves visual fluorescence sensing detection toward TNP at a limit of detection as low as 2.25 µM. Moreover, during the detection process, unexpectedly, TNP exhibits a selective etching effect on Sr-tcbpe, which could drill nano holes with different sizes on the surface area of MOF materials to a certain extent, achieving the conversion of chemical energy to mechanical energy. In addition, the successful preparation of a portable sensor Sr-tcbpe@gypsum block provides a platform for the perfect combination of mechanochromic fluorescence behavior and visualization detection toward TNP. It lays the foundation for the practical application of MOF materials in daily life.

HCR/DNAzyme-triggered cascaded feedback cycle amplification for self-powered dual-photoelectrode detection of femtomolar HPV16.

For high-performance dual-photoelectrode assay, developing a pair of photoactive materials with well-matched band structure and the design of a powerful sensing strategy are highly desirable. Herein, the Zn-TBAPy pyrene-based MOF and BiVO4/Ti3C2 Schottky junction were employed as photocathode and photoanode to form an efficient dual-photoelectrode system. The integration of the cascaded hybridization chain reaction (HCR)/DNAzyme-assisted feedback amplification with DNA walker-mediated cycle amplification strategy realizes femtomolar HPV16 dual-photoelectrode bioassay. Through the activation of the HCR cascaded with the DNAzyme system in the presence of HPV16, plentiful HPV16 analogs are generated that leads to exponential positive feedback signal amplification. Meanwhile on the Zn-TBAPy photocathode, the NDNA hybridizes with the bipedal DNA walker followed by circular cleavage by Nb.BbvCI NEase, producing a dramatically enhanced PEC readout. The achieved ultralow detection limit of 0.57 fM and a wide linear range of 10-6 nM-103 nM showcase the excellent performance of the developed dual-photoelectrode system.

A UOF based on a cyclotriphosphazene skeleton: fluorescence sensing of different substituted aldehydes and NACs.

A novel uranyl organic framework (U-hdpcp) based on flexible cyclic triphosphazene polycarboxylate ligands was prepared, which possesses the ability to sense aromatic aldehyde solutions (benzaldehyde, salicylaldehyde and 2-bromobenzaldehyde) and nitro compounds (2,4,6-trinitrophenol, 2,4-dinitrophenol and o-nitrophenol). A fluorescent thin film based on U-hdpcp@PVA with the ability to sense aldehyde vapors was prepared via a spin coating method. The work expands the library of UOF materials based on large-sized carboxylic acid ligands and demonstrates promising applications in the field of fluorescent sensors.

Neutral mononuclear, dinuclear, tetranuclear d7/d10 metal complexes containing bis-pyrazole/pyridine ligands supported by 2,6-bis(3-pyrazolyl)pyridine: synthesis, structure, spectra, and catalytic activity.

A series of novel bis-pyrazole/pyridine complexes, [Zn(2)(HL(1))(2)(µ(2)-SO(4))](2)·EtOH·H(2)O (1), [Co(2)(HL(1))(2)(µ(2)-SO(4))](2)·2DMF·6H(2)O (2), [Zn(4)(HL(1))(4)(µ(4)-SO(4))][OH](2) (3), [Zn(2)(HL(2))(2)(µ(2)-SO(4))]·2H(2)O (4), [Zn(H(2)L(2))(H(2)O)(2)](SO(4))·0.87H(2)O (5) (H(2)L(1) = 2,6-di-(5-phenyl-1H-pyrazol-3-yl)pyridine, H(2)L(2) = 2,6-di-(5-methyl-1H-pyrazol-3-yl)pyridine), were synthesized hydrothermally from the self-assembly of Zn(II) or Co(II) with different types of bipyrazolyl/pyridine derivative ligands. All the complexes were characterized by elemental analysis, IR and UV-vis spectroscopy, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. Structural analyses revealed that metal atoms (Zn and Co) in complexes 1-5 are five-coordination modes, forming slightly distorted trigonal bipyramidal geometries. In complexes 1-3, H(2)L(1) ligand connected the two metal centers via the tetradentate fashion, and the same form of connection was found in complex 4 with H(2)L(2) ligand. While in complex 5, H(2)L(2) only connected with one metal center via the tridentate fashion, which was different from those in complexes 1-4. Additionally, there are abundant hydrogen bonding interactions in complexes 1-4. Interestingly, for hydrogen bonding connecting fashions being different, the molecules for the complexes 1 and 4 are held together by the hydrogen bond to form a 1D supramolecular structure, whereas complexes 2 and 3 are a hydrogen bonded dimer. In addition, quantum chemical calculations for 1, 3, and 4, thermal behaviors and photoluminescent properties for 1 and 3-5 were performed and discussed in detail. In the mean time, we found that these complexes had potential catalytic activity for the oxidation reaction of cyclohexane.

Cu(II) and Zn(II) frameworks constructed by directional tuning of diverse substituted groups on a triazine skeleton and supermassive adsorption behavior for iodine and dyes.

The controllable design, synthesis and functional properties of a series of triazine tetratopic carboxylic MOFs have always been hotspots and challenges for research. Based on the characterization of the C-Cl bond on the triazine skeleton being easily substituted by some functional groups, we designed and synthesized a series of triazine tetratopic carboxylic Cu(II) and Zn(II) MOFs via the reaction of Cu(NO3)2·2.5H2O and ZnSO4·7H2O, as well as triazine tetratopic carboxylic H4TDBA-Cl (H4TBDA-Cl = 5,5'-((6-chloro-1,3,5-triazine-2,4-diyl)bis(azanediyl))diisophthalic acid) under hydrothermal conditions. During the process of synthesizing, the C-Cl bond on the triazine skeleton of the ligand was substituted with different groups, which formed the complexes ([Cu2(TBDA-Cl)(H2O)·10DMF·30H2O]n) (DMF = N,N-dimethylformamide) (1), N(Me)2 -[(CH3)2NH2]4·[Zn3(HTBDA-N)2(SO4)2]n (2) and H ([Cu2(TBDA-H)(H2O)]n) (3), respectively. It is worth noting that the in situ substitution reaction occurred for complexes 2 and 3 during the process of synthesis. Also, the structural analysis showed that the molecules in complexes 1-3 were connected with different building blocks to form different three-dimensional structures. We performed iodine adsorption experiments on the three complexes and found that there was a significant relationship between the structural configuration and adsorption behaviour. The results showed that the complex 1 with the Cl atom on the triazine skeleton could have a boosting effect on adsorption with iodine. It displayed a remarkable adsorption effect for iodine (in the solution of water: 7.6 g g-1 and in the solution of cyclohexane: 548.2 mg g-1). In addition, it also displayed the adsorption effect for JGB dye (204.9 mg g-1). For complex 2, it displayed an uptake effect for iodine in the solution of cyclohexane (529 mg g-1). The possible adsorption mechanism was also investigated. By comparison, we found that chlorine atoms could play an important role in the adsorption processes. The adsorption capacity of complex 1 (containing the chlorine atom in the structure) was much higher than that for complex 3.

Does Twisted π-Conjugation Framework Always Induce Efficient Intersystem Crossing? A Case Study with Benzo[b]- and [a]Phenanthrene-Fused BODIPY Derivatives and Identification of a Dark State.

The photophysical properties, especially the intersystem crossing (ISC) of two heavy-atom-free BODIPY derivatives with twisted π-conjugated frameworks (benzo[b]-fused BODIPY, BDP-B; and [a]phenanthrene-fused BODIPY, BDP-P), are studied with steady-state and time-resolved optical and electron paramagnetic resonance (TREPR) spectroscopic methods as well as with ADC(2) theoretical investigations. Interestingly, BDP-B has a planar π-conjugation framework, but it displays weaker UV-vis absorption (ε = 3.8 × 104 M-1 cm-1 at 569 nm) and fluorescence (ΦF < 0.1%), a short-lived singlet-excited state (fluorescence lifetime, τF = 0.2 ns), and a long-lived triplet state (τT = 132.3 µs). In comparison, the more twisted BDP-P shows stronger UV-vis absorption (ε = 9.8 × 104 M-1 cm-1 at 640 nm) and fluorescence (ΦF = 70%), longer singlet-excited-state lifetime (τF = 6.4 ns), and shorter triplet-state lifetime (τT = 18.9 µs). In contrast to helicenes (ΦT = ca. 90%), the ISC of BDP-P and BDP-B is nonefficient (ΦT < 23%). The electron spin selectivity of the ISC of the derivatives is different, manifested by the phase pattern of the TREPR spectra as AAEAEE and EEEAAA for BDP-B and BDP-P, respectively. The spatially confined T1 state wave function of the twisted molecule keeps the T1 state energy high (1.44-1.61 eV). A dark S1 state was identified for BDP-B. This work demonstrated that the twisted π-conjugated framework does not necessarily induce efficient ISC and we found a dark singlet state for BODIPY, which is rare.

[Comparative research on light-induced surface electron behavior of cobalt complexes].

Six cobalt complexes, Co(Hz2O)6.H2btec(1); {[Co2(HCOO)6].CH3OH}n(2); {[Co(4,4'-bipy)2(H2O)4].suc.4H2O)}n(3); Co(NA)2(H2O)4(4); [Co(mal)(4,4'-bipy)H2O]n(5) and [Co(HCOO)4Co(H2O)4]n(6), were synthesized through hydrothermal method. UV-Vis absorption spectra and surface photovoltage spectra of the complexes were detected and the structures of the complexes were determined by single-crystal X-ray diffraction. There are positive responses in the range of 300-800 nm in the SPS. There are good corresponding relationships between response bands of SPS and absorption peaks of UV-Vis absorption spectra by the comparison. Comparing the SPS of six complexes, the valence, coordination mode and coordination micro-environment affect the position and the shape of the response bands.

Two new scorpionates vanadium haloperoxidases model complexes: synthesis and structure of VO(O2)(pzH)(HB(pz)3) and VO(O2)(pzH)(B(pz)4) (pzH = pyrazole(C3H4N2)).

Using vanadate, poly(1H-pyrazol-1-yl)borate and pyrazole as starting materials, two new neutral peroxovanadium(V) complexes with poly(1H-pyrazol-1-yl)borate, VO(O(2))(pzH)(HB(pz)(3))(1) and VO(O(2))(pzH)(B(pz)(4))(2), were synthesized successfully. Both complexes were characterized by elemental analysis, IR, UV-vis and NMR spectra. And the structure of complex 1 was determined by X-ray diffraction, which is somewhat relevant for haloperoxidase enzymes. Cytotoxic effects also are discussed on 3T3 cell proliferation. In the concentration range (0.1-100mumol), both complexes have an inhibiting cellular proliferation effect. When the cells cultivated with the complexes at high dose, the toxicity effect of both complexes is more and more predominant.