Colorimetric assays have drawn increasing research interest with respect to the quantitative detection of hydrogen peroxide (H 2 O 2 ) based on artificial enzymes because of their advantages with respect to natural enzymes, including design flexibility, low cost, and high stability. Regardless, the majority of the artificial enzymes exhibit low affinity to H 2 O 2 with large Michaelis−Menten constants (K m ). This indicates that the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue-colored oxTMB requires a high H 2 O 2 concentration, hindering the sensitivity of the colorimetric assay. To address this problem, novel reduced Co 3 O 4 nanoparticles (R-Co 3 O 4 ) have been synthesized in this study via a step-by-step procedure using ZIF-67 as the precursor. R-Co 3 O 4 exhibits a considerably enhanced peroxidase-like activity when compared with that exhibited by pristine Co 3 O 4 (P-Co 3 O 4 ). The catalytic process in the case of R-Co 3 O 4 occurs in accordance with the typical Michaelis−Menten equation, and the affinity of R-Co 3 O 4 to H 2 O 2 is apparently higher than that of P-Co 3 O 4 . Furthermore, the density functional theory calculations revealed that the introduction of oxygen vacancies to R-Co 3 O 4 enhances its H 2 O 2 adsorption ability and facilitates the decomposition of H 2 O 2 to produce •OH radicals, resulting in improved peroxidase-like activity. A simple and convenient colorimetric assay has been established based on the excellent peroxidase-like activity of R-Co 3 O 4 for detecting H 2 O 2 in concentrations of 1−30 μM with a detection limit of 4.3 × 10 −7 mol/L (S/N = 3). Furthermore, the R-Co 3 O 4 -based colorimetric method was successfully applied to glucose detection in human serum samples, demonstrating its potential for application in complex biological systems.

An optically active porphyrin-pentapeptide conjugate 1, actually a porphyrinato zinc complex covalently linked with a glycinyl-alanyl-glycinyl-alanyl-glycine (GAGAG) peptide chain, was designed and synthesized. The self-assembly properties of this novel porphyrin-pentapeptide conjugate in THF/nhexane and THF/water were comparatively investigated by electronic absorption, circular dichroism (CD), IR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) technique. Associated with the different secondary conformation of the pentapeptide chain covalently linked to the porphyrin ring in different solvent systems, self-assembly of conjugate 1 leads to the formation of nanofibers with right-handed helical arrangement and nanotubes with left-handed helical arrangement in a stack of porphyrin chromophores according to the CD spectroscopic result in apolar THF/n-hexane (1 : 3) and polar THF/water (1 : 3) system depending on the cooperation between intramolecular or intermolecular hydrogen bonding interaction with chiral discrimination between pentapeptide chains and porphyrin-porphyrin interactions in the direction parallel to the tetrapyrrole ring of neighboring conjugate molecules. IR spectroscopic result clearly reveals the a-helix and b-sheet secondary conformation, respectively, employed by the pentapeptide chain attached at the porphyrin core in the nanostructures formed in THF/n-hexane (1 : 3) and THF/ water (1 : 3). The X-ray diffraction (XRD) result confirms that in the nanotubes, a dimeric supramolecular bilayer structure was formed through an intermolecular hydrogen bonding interaction between two conjugate molecules which, as the building block, self-assembles into the target nanostructures. These results clearly reveal the effect of a secondary conformation of pentapeptide chain in the conjugate molecule on the packing mode of porphyrin chromophore, supramolecular chirality, and morphology of the self-assembled nanostructure. The present result represents not only the first example of organic nanostructures self-assembled from a covalently linked porphyrin-pentapeptide conjugate, but more importantly the first effort towards controlling and tuning the morphology and in particular the supramolecular chirality of porphyrin nanostructures via tuning the secondary conformation of peptides in different solvent systems, which is helpful towards understanding, designing, preparing, and mimicking the structure and role of naturally occurring porphyrin-peptide conjugates. In addition, both nanofibers and nanotubes were revealed to show good semiconducting properties.

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Cystosepiment-like cobalt nanoparticles@N-doped carbon composite named Co-NPs@NC with highly efficient electrocatalytic performance for oxygen evolution reaction was prepared from carbonization of N-doped Co-MOFs. The optimized Co-NPs@NC-600 shows overpotentials of 315 mV to afford a current density of 10 mA·cm−2. Meanwhile, the electrocatalys presents excellent long-term durability. The outstanding electrocatalytic performance can be attributed to the unique cystosepiment-like architecture with high specific surface area (214 m2/g), high conductivity of N-doped carbon and well-distributed active sites.

(R)- and (S)-enantiomers of optically active metal free tetrakis[11,12:13,14-di(1',2'-naphtho)-1,4,7,10,15,18-hexaoxacycloeicosa-2,11,13-trieno]-phthalocyanine and their zinc complexes, (R)- and (S)-H(2)Pc (1) and (R)- and (S)-ZnPc (2), were prepared from the tetramerization of corresponding phthalonitriles, (R)- and (S)-2,3-(4',5'-dicyanobenzo)-11,12:13,14-di(1',2'-naphtho)-1,4,7,10,15,18-hexaoxacycloeicosa-2,11,13-triene, in the absence and presence of Zn(OAc)(2).2H(2)O template, respectively, promoted by organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Their self-assembly behavior in the absence and presence of 4,4'-bipyridine has been comparatively investigated by electronic absorption and circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) technique, and X-ray photoelectron spectroscopy (XPS). The metal free phthalocyanine self-assembles into highly ordered fibrous nanostructures (ca. 3 microm length, 70 nm width, and 125 nm helical pitch) with left-handed and right-handed helicity for (R)-1 and (S)-1, respectively, through the hierarchical manner via one-dimensional helices with chirality determined by the optically active binaphthyl side chains. In contrast, self-assembly of the phthalocyaninato zinc analogue leads to the formation of nanoparticles. However, in the presence of 4,4'-bipyridine, additionally formed metal-ligand Zn-N(4,4'-bipyridine) coordination bonds between the nitrogen atoms of additive 4,4'-bipyridine molecule and the zinc center of (R)- and (S)-2 molecules together with pi-pi interaction and chiral discrimination of chiral side chains induce a right-handed and left-handed helical arrangement in a stack of (R)- and (S)-2 molecules, respectively, which further hierarchically packs into highly ordered fibrous nanostructures of average tens of micrometers in length, 30 nm width, and 106 nm helical pitch with the same helicity to the stack, revealing the effect of metal-ligand coordination bonding interaction on the morphology, dimension, handedness, and helical pitch of self-assembled nanostructures.

A 3D porous framework ([Co 1.5 (tib)(dcpna)]·6H 2 O) (1) with a Wei topology has been synthesized by solvothermal reaction of 1,3,5-tris(1-imidazolyl)-benzene (tib), 5-(3 ,5 -dicarboxylphenyl)nicotinic acid (H 3 dcpna) and cobalt nitrate. The electrocatalytic activity for water oxidation of 1 has been investigated in alkaline solution. Compound 1 exhibits good oxygen evolution reaction (OER) activities in alkaline solution, exhibiting 10 mA·cm −2 at η = 360 mV with a Tafel slope of 89 mV·dec −1 . The high OER activity can be ascribe to 1D open channels along b axis of 1, which expose more activity sites and facilitate the electrolyte penetration.

Optically active metal‐free phthalocyanine (1) decorated with four octyl chains linked through binaphthyl units to the phthalocyanine ring was designed and prepared. This compound was characterized by a wide range of spectroscopic methods in addition to elemental analysis. By employing a solution injection method, both the (R) and (S) enantiomers self‐assemble into nanoparticles. Surprisingly, with the addition of a small amount of cetyltrimethylammonium bromide (CTAB), nanostructures with hollow‐sphere morphologies were formed. The hollow‐spherical structure was determined by transmission electronic microscopy and scanning electronic microscopy. X‐ray photoelectron spectroscopy together with FTIR spectra indicates the supramolecular structures formed from the metal‐free phthalocyanine molecules. Low‐angle X‐ray diffraction reveals the stacked phthalocyanine molecules with a face‐to‐face configuration in the nanoscale hollow spheres formed with the help of CTAB surfactant. The formation of H‐aggregates in the nanoscale hollow spheres is further confirmed by electronic absorption spectroscopic result. This work, representing the first example of controllable organic nanostructures with a hollow sphere morphology fabricated from phthalocyanine provides an effective method towards phthalocyanine hollow nanospheres.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

An optically active metal-free porphyrin (1) with four chiral binaphthyl units attached at the meso-phenyl substituents through crown ether moieties has been designed, synthesized, and characterized. Its self-assembly behavior in the absence and presence of K + was comparatively investigated by electronic absorption and circular dichroism (CD) spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), atom force microscopy (AFM), and energy-dispersive X-ray (EDX) spectroscopy. In the absence of K + , metal-free porphyrin self-assembles into nanoparticles depending mainly on the van der Waals interaction among neighboring metal-free molecules. In the presence of K + , ad-