Unprecedented POSS-Linked 3D Covalent Organic Frameworks with 2-Fold Interpenetrated scu or sqc Topology Regulated by Porphyrin Center for Photocatalytic CO2 Reduction.

The synthesis and characterization of porphyrin center regulated three-dimensional covalent organic frameworks (COFs) with 2-fold interpenetrated scu or sqc topology have been investigated. These COFs exhibit unique structural features and properties, making them promising candidates for photocatalytic applications in CO2 reduction and artemisinin synthesis. The porphyrin center serves as an anchor for metal ions, allowing precise control over structures and functions of the frameworks. Furthermore, the metal coordination within the framework imparts desirable catalytic properties, enabling their potential use in photocatalytic reactions. Overall, these porphyrin center regulated metal-controlled COFs offer exciting opportunities for the development of advanced materials with tailored functionalities.

Fabrication of Novel g-C3N4@Bi/Bi2O2CO3 Z-Scheme Heterojunction with Meliorated Light Absorption and Efficient Charge Separation for Superior Photocatalytic Performance.

Herein, a novel g-C3N4@Bi/Bi2O2CO3 Z-scheme heterojunction was synthesized via simple methods. UV/Vis diffuse reflectance spectroscopy (DRS) revealed that the visible light absorption range of heterojunction composites was broadened from 400 nm to 500 nm compared to bare Bi2O2CO3. The XRD, XPS and TEM results demonstrated that metal Bi was introduced into g-C3N4@Bi/Bi2O2CO3 composites, and Bi may act as an electronic bridge in the heterojunction. Metal Bi elevated the separation efficiency of carriers, which was demonstrated by photocurrent and photoluminescence. The performance of samples was assessed via the degradation of Rhodamine B (RhB), and the results exhibited that g-C3N4@Bi/Bi2O2CO3 possessed notably boosted photocatalytic activity compared with g-C3N4, Bi2O2CO3 and other binary composites. The heterojunction photocatalysts possessed good photostability and recyclability in triplicate cycling tests. Radical trapping studies identified that h+ and •O2- were two primary active species during the degradation reaction. Based on the energy band position and trapping radical experiments, the possible reaction mechanism of the indirect Z-scheme heterojunction was also proposed. This work could provide an effective reference to design and establish a heterojunction for improving the photocatalytic activity of Bi2O2CO3.

Rare-earth based tetrapyrrolic sandwiches: chemistry, materials and applications.

The unique properties of natural tetrapyrrolic compounds have inspired the rapid growth of research interest in the design and synthesis of artificial porphyrinoids and their metal complexes as a basis of modern functional materials. A special role in the design of such materials is played by sandwich complexes formed by tetrapyrrolic macrocycles with rare earth elements, especially lanthanides. The development of synthetic approaches to the functionalization of tetrapyrrolic compounds and their rare earth complexes has facilitated the intensive development of new applications over the last decade. As a way of expanding the functionalities of rare earth complexes, sophisticated examples have been obtained, including mixed-ligand complexes, π-extended analogues, covalently linked and fused sandwiches, complexes with less-common tetrapyrrols, sandwiches with non-tetrapyrrolic macrocycles and even complexes containing up to six stacked ligands. This review intends to offer a general overview of the preparation of such sophisticated REE tetrapyrrolic sandwiches over the last decade as well as emphasizes the current challenges and perspectives of their application in areas such as single-molecule magnetism (SMM), organic field-effect transistors (OFET), conductive materials and nonlinear optics (NLO).

A porphyrin-triazatruxene dyad for ratiometric two-photon fluorescent sensing of intracellular viscosity.

By combining an electron-rich triazatruxene unit (TAT) to an electron-deficient zinc porphyrin fluorophore (ZnPor) via an ethynyl bridge, a new two-photon fluorescent viscosity rotor (TAT-ZnPor) with typical donor-π-acceptor (D-π-A) electronic configuration was developed for the ratiometric two-photon fluorescent detection of intracellular viscosity. The TAT-ZnPor dyad exhibited highly improved fluorescence quantum yield (Φem = 0.40) and two-photon absorption cross-section (δTPA = 811 GM) in comparison to the individual components. In the methanol/glycerol system, TAT-ZnPor showed sensitive fluorescence responses toward the change of viscosity. Upon elevating the viscosity from 0.59 to 947 cp, the blue emission band around 410 nm gradually enhanced, while the red band at 647 nm concomitantly quenched, leading to a remarkable intensity ratio (I410/I647) change from 0.70 to 81 (116-fold). TAT-ZnPor also displayed good cell imaging performance under one- and two-photon excitation, and strong mitochondria targeting ability in living cells, thus was successfully applied in detecting the change of mitochondrial viscosity during the nystatin-induced degeneration.

Perspectives on Ligand Properties of N-Heterocyclic Carbenes in Iron Porphyrin Complexes.

There has been considerable research interest in the ligand nature of N-heterocyclic carbenes (NHCs). In this work, two six-coordinate NHC iron porphyrin complexes [FeII(TTP)(1,3-Me2Imd)2] (TTP = tetratolylporphyrin, 1,3-Me2Imd = 1,3-dimethylimidazol-2-ylidene) and [FeIII(TDCPP)(1,3-Me2Imd)2]ClO4 (TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin) are reported. Single-crystal X-ray characterizations demonstrate that both complexes have strongly ruffled conformations and relatively perpendicular ligand orientations which are forced by the sterically bulky 1,3-Me2Imd NHC ligands. Multitemperature (4.2-300 K) and high magnetic field (0-9 T) Mössbauer and low-temperature (4.0 K) EPR spectroscopies definitely confirmed the low-spin states of [FeII(TTP)(1,3-Me2Imd)2] (S = 0) and [FeIII(TDCPP)(1,3-Me2Imd)2]ClO4 (S = 1/2). The similarity of 1,3-Me2Imd and imidazole, as well as the well-established correlations between the ligand nature and spectroscopic characteristics of [FeII,III(Porph)(L)2]0,+ (Porph: porphyrin; L: planar base ligand) species, allowed direct comparisons between the pair of ligands which revealed for the first time that NHC has a stronger π-acceptor ability than imidazoles, in addition to its very strong σ-donation.

Stem cells from human exfoliated deciduous teeth affect mitochondria and reverse cognitive decline in a senescence-accelerated mouse prone 8 model.

BACKGROUND AIMS: Stem cell therapy is a novel therapy being explored for AD. The molecular mechanism of its effect is still unclear. The authors investigated the effects and mechanism by injection of SHEDs into an AD mouse model. METHODS: SHEDs were cultured in vitro and injected into AD SAMP8 mice by caudal vein, and SHEDs labeled via synthetic dye showed in vivo migration to the head. The cognitive ability of SAMP8 mice was evaluated via Barnes maze and new object recognition. The pathological indicators of AD, including Tau, amyloid plaques and inflammatory factors, were examined at the protein or RNA level. Next, macro-proteomics analysis and weighted gene co-expression network analysis (WGCNA) based on protein groups and behavioral data were applied to discover the important gene cluster involved in the improvement of AD by SHEDs, which was further confirmed in an AD model in both mouse and cell lines. RESULTS: SHED treatment improved the cognitive ability and pathological symptoms of SAMP8 mice. Proteomics analysis indicated that these improvements were tightly related to the mitochondria, which was proved through examination of the shape and function of mitochondria both in vivo (SAMP8 brain) and in vitro (SH-SY5Y cells). Finally, the core targets of SHEDs in the mitochondrial pathway, Hook3, Mic13 and MIF, were screened out and confirmed in vivo. CONCLUSIONS: SHED treatment significantly relieved AD symptoms, improved cognitive ability and reversed memory loss in an AD mouse model, possibly through the recovery of dysfunctional mitochondria. These results raise the possibility that SHED may ease the symptoms of AD by targeting the mitochondria.

Rational Modification of Two-Dimensional Donor-Acceptor Covalent Organic Frameworks for Enhanced Visible Light Photocatalytic Activity.

Covalent organic frameworks (COFs) are promising crystalline materials for photocatalytic solar- to hydrogen-energy conversion due to the tunable chemical structures and energy band gaps. Herein, we report a chemical modification strategy for improving the photocatalytic activity of COFs. A benzene-1,3,5-tricarbaldehyde (BT)- and benzothiadiazole derivative-based two-dimensional donor-acceptor (D-A) COF, denoted as BT-COF, were fabricated and further modified by using an alternative electron-donating unit, 2-hydroxybenzene-1,3,5-tricarbaldehyde (HBT), to the polycondensation reaction, yielding HBT-COF with an enhanced internal D-A effect and hydrophilicity. Interestingly, the photocatalytic H2 production rate of HBT-COF reaches 19.00 µmol h-1, which is 5 times higher than that of BT-COF (3.40 µmol h-1) under visible light irradiation. The increase in photocatalytic activity of HBT-COF is rationally attributed to finely tuned energy levels and improved wettability, which in turn leads to broadened visible light absorption, efficient photoinduced charge separation and transfer, and enhanced interactions between the COF catalyst and reaction substrates. The present results demonstrate that a subtle structural modification can significantly modulate the band structure and interfacial property, thus providing a feasible strategy for the optimization of COF-based photocatalytic systems.

Porphyrin-Based Metal-Organic Frameworks for Efficient Photocatalytic H2 Production under Visible-Light Irradiation.

Metal-organic frameworks (MOFs) are important photocatalytic materials for H2 production. To clarify the structure-function relationship and improve the photocatalytic activity, herein we explored a series of porphyrin-based zirconium MOFs (PCN-H2/Ptx:y, where x:y = 4:1, 3:2, 2:3, and 0:1) containing different ratios of H2TCPP and PtIITCPP [TCPP = tetrakis(4-carboxyphenyl)porphyrinate] as isostructural ligands and Zr6 clusters as nodes. Under visible-light irradiation, PCN-H2/Pt0:1 shows the highest average H2 evolution reaction rate (351.08 µmol h-1 g-1), which decreases along with lowering of the ratio of PtIITCPP in the PCN-H2/Ptx:y series. The differences in photocatalytic activity are attributed to more uniformly dispersed Pt2+ ions in PCN-H2/Pt0:1, which promotes charge transfer from porphyrins (photosensitizers) to PtII ions (catalytic centers), leading to efficient charge separation in the MOF materials. The bifunctional MOFs with photosensitizers and catalytic centers provide new insight for the design and application of porphyrin-based photocatalytic systems for visible-light-driven H2 production.

Multipolar Porphyrin-Triazatruxene Arrays for Two-Photon Fluorescence Cell Imaging.

Two-photon excited fluorescent (TPEF) materials are highly desirable for bioimaging applications owing to their unique characteristics of deep-tissue penetration and high spatiotemporal resolution. Herein, by connecting one, two, or three electron-deficient zinc porphyrin units to an electron-rich triazatruxene core via ethynyl π-bridges, conjugated multipolar molecules TAT-(ZnP)n (n=1-3) were developed as TPEF materials for cell imaging. The three new dyes present high fluorescence quantum yields (0.40-0.47) and rationally improved two-photon absorption (TPA) properties. In particular, the peak TPA cross section of TAT-ZnP (436 GM) is significantly larger than that of the ZnP reference (59 GM). The δTPA values of TAT-(ZnP)2 and TAT-(ZnP)3 further increase to 1031 and up to 1496 GM, respectively, indicating the effect of incorporated ZnP units on the TPA properties. The substantial improvement of the TPEF properties is attributed to the formation of π-conjugated quadrapole/octupole molecules and the extension of D-π-A-D systems, which has been rationalized by density function theory (DFT) calculations. Moreover, all of the three new dyes display good biocompatibility and preferential targeting ability toward cytomembrane, thus can be superior candidates for TPEF imaging of living cells. Overall, this work demonstrated a promising strategy for the development of porphyrin-based TPEF materials by the construction and extension of D-π-A-D multipolar array.

Intermolecular Chirality Modulation of Binaphthalene-Bridged Bisporphyrins With Chiral Diamines.

A new pair of 2,2'-diamino-1,1'-binaphthyl linked porphyrin dimers, (R)-/(S)-H, were synthesized to study their supramolecular interactions with a pair of chiral diamines ((R)-/(S)-PPDA) by using UV-Vis absorption, fluorescence and NMR titrations. The spectroscopic titrations indicated that sandwich-type 1:1 complexes were formed at low guest concentration and then transformed to 1:2 open complexes at high guest concentration. The supramolecular interactions afforded sensitive circular dichroism responses, and the CD signs of the 1:1 complexes are decided by the stereostructure of chiral diamine guests. Moreover, due to the shortened linking units, (R)-/(S)-H show more sensitive and predicable CD response than the previously reported hosts (R)-/(S)-H1 and this can be reasonably explained by DFT molecular modeling. The present results suggest (R)-/(S)-H are promising for chiral optical sensing.

Manganese(III) Porphyrin-Based Magnetic Materials.

Manganese(III) porphyrin complexes with various metal-containing/non-metal bridges reported during the past two decades, including their structural characteristics and magnetic properties, are summarized. As the porphyrin ligands usually adopt a planar chelate form, it is possible that the porphyrin-based complexes, being a coordination-acceptor building block, have two coordination labile sites in trans positions. In particular, the coordination labile sites in an octahedral field face the direction of the Jahn-Teller elongated axis occupying the dz2 orbital. As a result of this characteristic orbital arrangement, the activity and magnetic-electronic properties of the manganese complexes can be tuned by modulating the porphyrin ligand, which is equatorially located around the manganese ion and coupled with the dx2-y2 orbital. The high-spin Mn(III) porphyrin complexes (S = 2) display strong magnetic uniaxial anisotropy with the Jahn-Teller axis as the magnetic easy axis. So far, various manganese(III) porphyrin magnetism systems, including multinuclear clusters, one-dimensional chains, and two- or three-dimensional networks, have been designed and structurally and magnetically characterized. This review shows that the manganese(III) porphyrin complexes have potential as versatile sources for the design of unique magnetic materials as well as other molecular functional materials with various structures.

Two-Photon Excited FRET Dyads for Lysosome-Targeted Imaging and Photodynamic Therapy.

Two-photon excitable fluorescent dyes with integrated functions of targeted imaging and photodynamic therapy (PDT) are highly desired for the development of cancer theranostic agents. Herein, fluorescence resonance energy transfer (FRET) dyads, AceDAN-H2Por-Lyso (1a) and AceDAN-ZnPor-Lyso (1b), were developed for two-photon excited (TPE) lysosome-targeted fluorescence imaging and PDT of cancer cells. Under one-photon or two-photon excitation, the AceDAN donor can effectively transfer the excited state energy to the porphyrin acceptor via high efficient FRET, leading to the generation of deep-red fluorescence and singlet oxygen for cell imaging and PDT, respectively. 1a and 1b exhibit high photocytotoxicity and low dark cytotoxicity, in addition to strong lysosomal targeting capability in living cells. By taking the advantages of the two-photon absorption properties of the AceDAN donor and the properly distributed S1 and T1 states of the porphyrin acceptor, the AceDAN-porphyrin dyads 1a and 1b have been successfully applied to TPE-fluorescence imaging for tracking the significant morphology changes of cancer cells under two-photon laser irradiation.

Lysosome-targeting ratiometric fluorescent pH probes based on long-wavelength BODIPY.

BODIPY-based probes were developed for the ratiometric fluorescence detection of pH values. They showed high sensitivity under acidic conditions via a protonation-modulated ICT mechanism and could selectively stain lysosomes, and thus could be applied for imaging and detecting abnormal pH decreases in live cells.

Ratiometric Fluorescent Detection of Pb2+ by FRET-Based Phthalocyanine-Porphyrin Dyads.

Sensitive and selective detection of Pb2+ is a very worthwhile endeavor in terms of both human health and environmental protection, as the heavy metal is fairly ubiquitous and highly toxic. In this study, we designed phthalocyanine-porphyrin (Pc-Por) heterodyads, namely, H2Pc-α-ZnPor (1) and H2Pc-ß-ZnPor (2), by connecting a zinc(II) porphyrin moiety to the nonperipheral (α) or peripheral (ß) position of a metal-free phthalocyanine moiety. Upon excitation at the porphyrin Soret region (420 nm), both of the dyads exhibited not only a porphyrin emission (605 nm) but also a phthalocyanine emission (ca. 700 nm), indicating the occurrence of intramolecular fluorescence resonance energy transfer (FRET) processes from the porphyrin donor to the phthalocyanine acceptor. The dyads can selectively bind Pb2+ in the phthalocyanine core leading to a red shift of the phthalocyanine absorption and thus a decrease of spectral overlap between the porphyrin emission and phthalocyanine absorption, which in turn suppresses the intramolecular FRET. In addition, the binding of Pb2+ can highly quench the emission of phthalocyanine by heavy-metal ion effects. The synergistic coupled functions endow the dyads with remarkable ratiometric fluorescent responses at two distinct wavelengths (F605/F703 for 1 and F605/F700 for 2). The emission intensity ratio increased as a linear function to the concentration of Pb2+ in the range of 0-4.0 µM, whereas the detection limits were determined to be 3.4 × 10-9 and 2.2 × 10-8 M for 1 and 2, respectively. Furthermore, by comparative study of 1 and 2, the effects of distance and relative orientation between Pc and ZnPor fluorophores on the FRET efficiency and sensing performance were highlighted, which is helpful for further optimizing such FRET systems.

Chiral Discrimination of Diamines by a Binaphthalene-Bridged Porphyrin Dimer.

A pair of 1,1'-binaphthalene-bridged bisporphyrins, (R)- and (S)-H1, were designed to examine their chiral discrimination abilities toward a range of model diamines by using UV-vis absorption, CD, and 1H NMR spectroscopy with the assistance of DFT molecular modeling. The spectroscopic titrations revealed that (R)-/(S)-H1 could encapsulate (R)-/(S)-DACH and (R)-/(S)-PPDA in the chiral bisporphyrin cavities, leading to the selective formation of sandwich-type 1:1 complexes via dual Zn-N coordination interactions. In particular, the chiral recognition energy (ΔΔG°) toward (R)-/(S)-DACH was evaluated to be -4.02 kJ mol-1. The binding processes afforded sensitive CD spectral changes in response to the stereostructure of chiral diamines. Remarkable enantiodiscrimination effects were also detected in the NMR titrations of (R)-/(S)-H1, in which the nonequivalent chemical shift (ΔΔδ) can reach up to 0.57 ppm for (R)-/(S)-DACH. However, due to the large steric effect, another chiral diamine ((R)-/(S)-DPEA) could not be sandwiched in the chiral bisporphyrin cavity; therefore, (R)-/(S)-DPEA could hardly be discriminated by (R)-/(S)-H1. The present results demonstrate a chiral bisporphyrin host with integrated CD and NMR chiral sensing functions and also highlight the binding-mode-dependent character of its enantiodiscrimination performance for different chiral guests.

Screening hybridomas for anabolic androgenic steroids by steroid analog antigen microarray.

BACKGROUND: Currently, dozens of anabolic androgenic steroids (AAS) are forbidden in the World Anti-Doping Agency Prohibited List, however, despite extensive investigation, there are still lots of AAS without corresponding monoclonal antibodies. RESULTS: A steroid analog antigen microarray made up of ten AAS was fabricated to screen the hybridoma and it was found an original unsuccessful clone turned out to be a candidate anti-boldenone antibody, without any cross-reactions with endogenous AAS or 44 different AAS standard reference materials tested. CONCLUSION: Our findings suggested that steroid analog antigen microarray could be a promising tool to screen and characterize new applications of antibodies for structure analogs, and this also exhibits the potential to fast identify effective epitopes of hybridomas in a single assay.

Annexin A2 as a target endothelial cell membrane autoantigen in Behçet's disease.

Cell membrane proteins are believed to play a critical role in the pathogenesis of autoimmune diseases. However, few membrane autoantigens have been linked with Behçet's disease. Here, a cell-chip was performed to identify autoantibody target cells, and the suspected autoantigens were detected using immunoblotting. The amino acid sequences of the detected proteins were determined using LC-MALDI-TOF/TOF. Putative proteins were recombinantly expressed and purified, and a corresponding ELISA was developed and clinically validated using real clinical samples. It was found that a 36-kDa membrane protein--annexin A2--was detected in approximately one-third of the patients' blood circulation. The immunohistochemistry results showed that annexin A2 was highly expressed in vascular endothelial cells. Moreover, vascular involvement was significantly higher in the anti-annexin A2 antibody-positive group versus the anti-annexin A2 antibody-negative group among all the clinical samples analyzed, indicating that annexin A2 is a novel endothelial cell membrane antigen involved in Behçet's disease.

Synergistic coupling of fluorescent "turn-off" with spectral overlap modulated FRET for ratiometric Ag+ sensor.

A useful strategy for ratiometric fluorescent detecting of Ag(+) is demonstrated. Upon selective binding of Ag(+) to a BODIPY-porphyrin dyad (1), the synergistic coupling of two functions, namely the suppressing of FRET from BODIPY donor to porphyrin acceptor and the fluorescence quenching of porphyrin acceptor, leads to exceptionally large changes in the intensity ratio of two distinct emissions (F513/F654) which allow for the ratiometric detecting of Ag(+) with excellent sensitivity in solution and living cells.

The supramolecular interaction mediated chiral 1D cyanide-bridged metamagnet: synthesis, crystal structures and magnetic properties.

Two cyanide-bridged enantiopure one-dimensional single chain complexes, [Mn((R,R)-Salcy)Fe(pcq)(CN)3]2n·1.5nDMF (1) and [Mn((S,S)-Salcy)Fe(pcq)(CN)3]2n·1.5nDMF (2), have been synthesized and structurally characterized. Systematically magnetic investigations show the antiferromagnetic coupling between the cyanide-bridged Mn(III)-Fe(III) centers and the interesting metamagnetic behavior at about 5.0 K resulted from the intermolecular π-π interaction.

Stereochemistry and solid-state structure of an intrinsically chiral meso-patterned porphyrin: case study by NMR and single-crystal X-ray diffraction analysis.

A C1-symmerical meso-substituted ABCD-type porphyrin, [5-phenyl-10-(2-hydroxynaphthyl)-15-(4-hydroxyphenyl)porphyrinato]zinc(II) (1), has been synthesized and characterized. The molecular structure of 1 has been determined by single-crystal X-ray diffraction analysis. The complex 1 crystallizes in a triclinic system with one pair of enantiomeric molecules per unit cell. Resolution of the racemic mixture has been achieved by chiral HPLC techniques. In particular, the absolute configurations of the enantiomers have been assigned from NMR spectroscopic analysis with L-Phe-OMe as the chiral solvating agent (CSA). The assignments have also been unambiguously confirmed by single-crystal X-ray diffraction analysis. The present results suggest that the CSA-NMR anisotropy strategy is applicable for the stereochemistry determination of chiral host-guest complexes with multiple intermolecular interactions. In addition, the multiple intermolecular interactions between the enantiomerically pure porphyrin S-1 and L-Phe-OMe are proved in the solid state by single-crystal X-ray diffraction analysis.