Design of single-porphyrin donors toward high open-circuit voltage for organic solar cells via an energy level gradient-distribution screening strategy of fragments: a theoretical study.

Open-circuit voltage (VOC) is a key factor for improving the power conversion efficiency (PCE) of bulk heterojunction (BHJ) organic solar cells (OSCs). At present, increasing attention has been devoted towards modifying π bridges in single-porphyrin small molecule donors with an A-π-D-π-A configuration to reduce the highest occupied molecular orbital (HOMO) levels and improve the VOC of devices. However, how to screen the π bridges is a key issue. In this work, nine π bridges were screened by the HOMO level gradient-distribution strategy of fragments (electron-donating donor (D), π bridges, and electron-withdrawing acceptor (A)), where fragments meeting the requirements were combined into five novel small molecule donors. Meanwhile, in order to test whether the strategy is beneficial to increasing VOC, [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) was selected as the acceptor material. The energy levels of all molecules were compared and the photoelectric properties (i.e., energy gap, energy driving force, reorganization energy, intermolecular charge transfer rate, charge recombination rate, and VOC) of the five small molecules were studied. The results showed that the HOMO levels of porphyrin donors could be significantly lowered via this strategy, and VOC was raised without losing the short-circuit current (JSC) and fill factor (FF) of the devices. Meanwhile, the designed five small molecules could be used as donor candidates to improve the performance of OSCs.

A Quninolylthiazole Derivatives as an ICT-Based Fluorescent Probe of Hg(II) and its Application in Ratiometric Imaging in Live HeLa Cells.

As a structural analogue of pyridylthiazole, 2-(2-benzothiazoyl)-phenylethynylquinoline (QBT) was designed as a fluorescent probe for Hg(II) based on an intramolecular charge transfer (ICT) mechanism. The compound was synthesized in three steps starting from 6-bromo-2-methylquinoline, with moderate yield. Corresponding studies on the optical properties of QBT indicate that changes in the fluorescence ratio of QBT in response to Hg(II) could be quantified based on dual-emission changes. More specifically, the emission spectrum of QBT before and after interactions with Hg(II) exhibited a remarkable red shift of about 120 nm, which is rarely reported in ICT-based fluorescent sensors. Finally, QBT was applied in the two-channel imaging of Hg(II) in live HeLa cells.

Polymorph of 4-(carbazol-9-yl)benzo-nitrile.

The asymmetric unit of the title compound, C(19)H(12)N(2), contains two independent mol-ecules with a similar structure. In the two mol-ecules, the dihedral angles between the carbazole ring system and the benzene ring are 47.9 (5) and 45.4 (4)°, similar to the value of 47.89 (6)° found in the previously reported structure [Saha & Samanta (1999 ▶). Acta Cryst. C55, 1299-1300]. In the crystal, there is a weak C-H⋯N hydrogen bond between the two independent mol-ecules.

3,6-Diiodo-9H-carbazole.

In the title compound, C(12)H(7)I(2)N, the tricyclic aromatic ring system is essentially planar, with an r.m.s. deviation of 0.0272 Å. The two I atoms are marginally out of plane, with the C-I bonds angled at 3.9 (2) and 1.1 (2)° with respect to the planes of their respective benzene rings, above and below the plane of the carbazole ring system. No classical hydrogen bonds are observed in the crystal structure.

The effect of heavy atoms replacement sites on the luminescent ways of D-A-D type diphenyl sulfone molecules: Thermally activated delayed fluorescence and phosphorescence.

To obtain efficient pure organic thermally activated delayed fluorescence (TADF) materials, introducing non-metal heavy atoms is the common molecular design strategy, enhancing the intrinsically weak spin-orbit coupling (SOC) between singlet and triplet excited states by heavy-atom effect. However, the effect of heavy atom replacement sites is rarely explored. Herein, two series of molecules are investigated on the basis of different heavy atoms replacement sites to reveal the inherent structure-property relationships. The results show that DMSeC-DPS, which O is replaced with Se in periphery of donor units, could exhibit enhanced TADF performance. Because (i) sufficiently small singlet-triplet states energy gap (ΔEST) and enhanced SOC as well as mixed CT/LE character in T1 state could facilitate reverse intersystem crossing process, and (ii) non-radiative consumption are decreased for S1→S0 transition. Additionally, replacement of As at the connection site between donor and acceptor units folds evidently the geometry, leading to much larger ΔEST and enhanced exponentially SOC between T1 and S0 state due to the great participation of heavy atoms of the frontier molecules orbitals and heavy-atom effect. The pure LE character leads to relative stability and slight non-radiative consumption in T1 state. The luminescent way of DMOC-As-DPS would be transformed to phosphorescence. This work provides updated theoretical perspective for the effect of heavy atoms replacement sites and proposes a design strategy for the utilization of non-metal heavy atoms in efficiency organic lighting emitting diodes.

Matrix Metalloproteinases (MMPs) in Targeted Drug Delivery: Synthesis of a Potent and Highly Selective Inhibitor against Matrix Metalloproteinase- 7.

BACKGROUND: Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that play a key role in both physiological and pathological tissue degradation. MMPs have reportedly shown great potentials in the degradation of the Extracellular Matrix (ECM), have shown great potentials in targeting bioactive and imaging agents in cancer treatment. MMPs could provoke Epithelial to Mesenchymal Transition (EMT) of cancer cells and manipulate their signaling, adhesion, migration and invasion to promote cancer cell aggressiveness. Therefore, targeting and particularly inhibiting MMPs within the tumor microenvironment is an effective strategy for cancer treatment. Based on this idea, different MMP inhibitors (MMPIs) have been developed to manipulate the tumor microenvironment towards conditions appropriate for the actions of antitumor agents. Studies are ongoing to improve the selectivity and specificity of MMPIs. Structural optimization has facilitated the discovery of selective inhibitors of the MMPs. However, so far no selective inhibitor for MMP-7 has been proposed. AIMS: This study aims to comprehensively review the potentials and advances in applications of MMPs particularly MMP-7 in targeted cancer treatment approaches with the main focus on targeted drug delivery. Different targeting strategies for manipulating and inhibiting MMPs for the treatment of cancer are discussed. MMPs are upregulated at all stages of expression in cancers. Different MMP subtypes have shown significant targeting applicability at the genetic, protein, and activity levels in both physiological and pathophysiological conditions in a variety of cancers. The expression of MMPs significantly increases at advanced cancer stages, which can be used for controlled release in cancers in advance stages. METHODS: Moreover, this study presents the synthesis and characteristics of a new and highly selective inhibitor against MMP-7 and discusses its applications in targeted drug delivery systems for therapeutics and diagnostics modalities. RESULTS: Our findings showed that the structure of the inhibitor P3' side chains play the crucial role in developing an optimized MMP-7 inhibitor with high selectivity and significant degradation activities against ECM. CONCLUSION: Optimized NDC can serve as a highly potent and selective inhibitor against MMP-7 following screening and optimization of the P3' side chains, with a Ki of 38.6 nM and an inhibitory selectivity of 575 of MMP-7 over MMP-1.