Selective Excited-State Dynamics in a Unique Set of Rationally Designed Ni Porphyrins

In this work, we report the design and photophysical properties of a unique class of Ni porphyrins, in which the tert-butyl benzene substituents at the meso positions of the macrocycle were tethered by ethers with alkyl linkers. This not only results in the permanently locked ruf distortion of the macrocycle but also enables the engineering of the degree of distortion through varying the length of alkyl linkers, which addressed the complication of uncertainty in the specific structural distortions that has long plagued the porphyrin photophysical community. Using advanced time-resolved optical and X-ray absorption spectroscopy, we observed tunability in the excited-state relaxation pathway depending on the degree of distortion and characterized the associated transient intermediate structure. These findings provide a new avenue to afford accessibility to a wide range of excited-state properties in nonplanar porphyrins

Synthesis of Novel Thiazolo[3,2-a]pyrimidine Compounds

A new class of thiazolo[3,2-a]pyrimidine compounds were synthesized by the reaction of 5-carbethoxyl-4-aryl-6-methyl-1,2,3,4-tetrahydropyrimidin-2-ones with dimethyl acetylenedicarboxylate. The reaction has the advantages of excellent yields and simple workup procedures. The products were characterized thoroughly by IR and NMR (H-1, C-13, COSY, HSQC and HMBC) together with elemental analysis. The X-ray crystallographic analysis of the 1,3-dipolar cycloaddition derivative of the title product provided the direct information for the structure of the product

Development of a Near Ground Remote Sensing System

Unmanned Aerial Vehicles (UAVs) have shown great potential in agriculture and are increasingly being developed for agricultural use. There are still a lot of experiments that need to be done to improve their performance and explore new uses, but experiments using UAVs are limited by many conditions like weather and location and the time it takes to prepare for a flight. To promote UAV remote sensing, a near ground remote sensing platform was developed. This platform consists of three major parts: (1) mechanical structures like a horizontal rail, vertical cylinder, and three axes gimbal; (2) power supply and control parts; (3) onboard application components. This platform covers five degrees of freedom (DOFs): horizontal, vertical, pitch, roll, yaw. A stm32 ARM single chip was used as the controller of the whole platform and another stm32 MCU was used to stabilize the gimbal. The gimbal stabilizer communicates with the main controller via a CAN bus. A multispectral camera was mounted on the gimbal. Software written in C++ language was developed as the graphical user interface. Operating parameters were set via this software and the working status was displayed in this software. To test how well the system works, a laser distance meter was used to measure the slide rail’s repeat accuracy. A 3-axis vibration analyzer was used to test the system stability. Test results show that the horizontal repeat accuracy was less than 2 mm; vertical repeat accuracy was less than 1 mm; vibration was less than 2 g and remained at an acceptable level. This system has high accuracy and stability and can therefore be used for various near ground remote sensing studies

Pseudocapacitance contribution in boron-doped graphite sheets for anion storage enables high-performance sodium-ion capacitors

Research on metal-ion hybrid capacitors is emerging as one of the hottest topics in energy storage fields because of their combination of high power and energy densities. To improve the sluggish faradaic reaction in traditional electrode materials for metal-ion hybrid capacitors, intercalation pseudocapacitive materials have been developed as attractive candidates. However, all the previously reported pseudocapacitances in intercalation/deintercalation reactions are based on cations (Li+, Na+, Zn2+etc.). In this work, we demonstrated the high pseudocapacitance contribution in boron-doped graphite (BG) sheets by taking advantage of anion storage. The BG electrode can reversibly store anions (PF6−) through both a surface-controlled pseudocapacitive reaction and a diffusion-limited intercalation/deintercalation reaction. The fabricated Na-ion hybrid capacitor with a BG cathode exhibits superior electrochemical performance. Density functional theory (DFT) calculation reveals that B-doping can significantly reduce the PF6− diffusion energy barrier in the graphite layers

Synthesis of Novel Thiazolo 3,2-a pyrimidine Compounds

A new class of thiazolo[3,2-a]pyrimidine compounds were synthesized by the reaction of 5-carbethoxyl-4-aryl-6-methyl-1,2,3,4-tetrahydropyrimidin-2-ones with dimethyl acetylenedicarboxylate. The reaction has the advantages of excellent yields and simple workup procedures. The products were characterized thoroughly by IR and NMR ((1)H, (13)C, COSY, HSQC and HMBC) together with elemental analysis. The X-ray crystallographic analysis of the 1,3-dipolar cycloaddition derivative of the title product provided the direct information for the structure of the product

Fixation of Zinc(II) Ion to Dioxygen in a Highly Deformed Porphyrin: Implications for the Oxygen Carrier Mechanism of Distorted Heme

Three <i>saddle</i>-type nonplanar zinc porphyrins strapped by two short alkyl linkers have been synthesized. The deformation induced by the linkers can cause a spectral red shift of >30 nm compared with the absorption maxima of regular porphyrins and can also regulate the electronic structure of the central zinc­(II) ion. The zinc­(II) ion then complexes and activates a free dioxygen to form a superoxide group ligand by enlarging the splitting of energy levels of d orbitals under strong core deformation. The fixation of dioxygen can be reasonably explained by the Dewar–Chatt–Duncanson model. These results indicate that this type of saddle porphyrin has the potential to be used as a new model system of heme

Fine-Tuning of Electronic Structure of Cobalt(II) Ion in Nonplanar Porphyrins and Tracking of a Cross-Hybrid Stage: Implications for the Distortion of Natural Tetrapyrrole Macrocycles

The core size of the porphyrin macrocycles was closely related to their stability of the different electron structure in the central metal ion. Cobalt­(II) ions can undergo a conversion in electron configurations upon N₄ core contraction of 0.05 Å in nonplanar porphyrins, and these ions still maintain low spin forms after and before conversion. The structural fine-tuning can induce the appearance of a cross-hybrid stage [d­(_{<i>x</i>²−<i>y</i>}^₂)­sp² ↔ d­(_<i>z</i>²)­sp²] based on quadrilateral coordination of the planar core. The results indicate that the configuration conversion plays a key role in electron transfer in redox catalysis involving cobalt complexes. The electronic properties of six monostrapped cobalt­(II) porphyrins were investigated by spectral, paramagnetic, and electrochemical methods. The macrocyclic deformations and size parameters of Co-containing model compounds were directly obtained from their crystal structures

MDMASNet: A Dual-task Interactive Semi-supervised Remote Sensing Image Segmentation Method

Remote sensing image (RSIs) segmentation is widely used in urban planning, natural disaster detection and many other fields. Compared with natural scene images, RSIs have higher resolution, complex imaging, and diverse object shapes and sizes, while semantic segmentation methods based on deep learning often require many data labels. In this paper, we propose a semi-supervised RSIs segmentation network with multi-scale deformable threshold feature extraction module and mixed attention (MDMANet). First, a pyramid ensemble structure is used, which incorporates deformable convolution and bole convolution, to extract features of objects with different shapes and sizes and reduce the influence of redundant features. Meanwhile, a mixed attention (MA) is proposed to aggregate long-range contextual relationships and fuse low-level features with high-level features. Second, an FCN-based full convolution discriminator task network is designed to help evaluate the feasibility of unlabeled image prediction results. We performed experimental validation on three datasets, and the results show that MDMANet segmentation provides more significant improvement in accuracy and better generalization than existing segmentation networks