Mild and Efficient Preparation of N-Heterocyclic Organic Molecules by Catalyst-free and Solvent-free Methods

AIMS

The small organic molecular compounds with biological activity containing C-C and C-N or C-O bonding were efficiently prepared without catalyst and solvent in the hydrothermal synthesis reactor.

OBJECTIVES

Our goal was to explore new applications for the more environmentally friendly and efficient synthesis of bis(indolyl)methyl, xanthene, quinazolinone, and N-heterocyclic derivatives in hydrothermal synthesis reactors under solvent-free and catalyst-free conditions.

METHODS

A greener and more efficient method was successfully developed for the synthesis of bis(indolyl)methyl, heteroanthracene, quinazolinone, and N-heterocyclic derivatives using a hydrothermal synthesis reactor in a solvent- and catalyst-free manner.

RESULTS

In a hydrothermal synthesis reactor, bis(indoyl)methyl, xanthene, quinazolinone, and N-heterocyclic derivatives were synthesized without catalysts and solvents.

CONCLUSION

Overall, it is proved once again that the catalyst-free and solvent-free synthesis method has universal value and is a more ideal and environmentally friendly new method, especially the hydrothermal reactor for synthesis.

PDI-Based Organic Small Molecule Regulated by Inter/Intramolecular Interactions for Efficient Solar Vapor Generation

Organic small molecules with processing feasibility, structural diversity, and fine-tuned properties have the potential applications in solar vapor generation. However, the common defects of narrow solar absorption, low photothermal conversion efficiency, and photobleaching result in limited materials available and unsatisfactory evaporation performance. Herein, the perylene diimide (PDI) derivatives are exploited as stable sunlight absorbers for solar vapor generation. Particularly, the N,N'-bis(3,4,5-trimethoxyphenyl)-3,4,9,10-perylenetetracarboxylic diimide (PDI-DTMA) is well-designed with donor-acceptor-donor configuration based on plane rigid PDI core. The efficient photothermal conversion is enabled through strong intermolecular π-π stacking and intramolecular charge transfer, as revealed by experimental demonstration and theoretical calculation. The PDI-DTMA with a narrow band gap of 1.17 eV exhibits expanded absorption spectrum and enhanced nonradiative transition capability. The 3D hybrid hydrogels (PPHs) combining PDI-DTMA and polyvinyl alcohol are constructed. With the synergistic effect of solar-to-heat conversion, thermal localization management, water activation, and unobstructed water transmission of PPHs, the high water evaporation rates can reach 3.61-10.07 kg m-2 h-1 under one sun. The hydrogels also possess great potential in seawater desalination and sewage treatment. Overall, this work provides valuable insights into the design of photothermal organic small molecules and demonstrates their potentials in solar water evaporation.

Remarkable Enhancement of Hole Mobility of Novel DA-D'-AD Small Molecules by Thermal Annealing: Effect of the D'-Bridge Block

Conjugated small molecules are advanced semiconductor materials with attractive physicochemical and optoelectronic properties enabling the development of next-generation electronic devices. The charge carrier mobility of small molecules strongly influences the efficiency of organic and hybrid electronics based on them. Herein, we report the synthesis of four novel small molecules and their investigation with regard to the impact of molecular structure and thermal treatment of films on charge carriers' mobility. The benzodithiophene-containing compounds (BDT) were shown to be more promising in terms of tuning the morphology upon thermal treatment. Impressive enhancement of hole mobilities by more than 50 times was found for annealed films based on a compound M4 comprising triisopropylsilyl-functionalized BDT core. The results provide a favorable experience and strategy for the rational design of state-of-the-art organic semiconductor materials (OSMs) and for improving their charge-transport characteristics.

Recent Advances in N-Heterocyclic Small Molecules for Synthesis and Application in Direct Fluorescence Cell Imaging

Nitrogen-containing heterocycles are ubiquitous in natural products and drugs. Various organic small molecules with nitrogen-containing heterocycles, such as nitrogen-containing boron compounds, cyanine, pyridine derivatives, indole derivatives, quinoline derivatives, maleimide derivatives, etc., have unique biological features, which could be applied in various biological fields, including biological imaging. Fluorescence cell imaging is a significant and effective imaging modality in biological imaging. This review focuses on the synthesis and applications in direct fluorescence cell imaging of N-heterocyclic organic small molecules in the last five years, to provide useful information and enlightenment for researchers in this field.

Anomalous Self-Optimizing Microporous Graphene-Based Lithium-ion Battery Anode from Laser Activation of Small Organic Molecules

Laser scribing technology is a straightforward technique to fabricate porous graphene, yet only conducted with polymeric precursors. Compared to polymers, molecular engineering of small organic molecules is much easier, which can be used to modify the graphene with tailored performance. Here we report the first employment of a laser to respectively transform small organic molecules, pentacene quinone and tetraazapentacene quinone (TAPQ), into graphene (P-LIG and N-LIG) as high-performance lithium-ion battery anodes. The TAPQ, as the N-fused molecular precursor, produces nitrogen-doped graphene. Both N-LIG and P-LIG exhibit significant self-enhancement of capacity upon cycling; the N-LIG anode delivers reversible capacities of 5863 mAh g^-1 at 0.2 A g^-1 and retains 1970 mAh g^-1 at 2 A g^-1 after another 500 cycles, which is the best performance for the graphene-type anode. Kinetics studies and structural characterizations verify that the surface- and diffusion-controlled processes are both progressively optimized, providing extra lithium storage upon cycling. It is also supported by small-angle X-ray scattering that the disordering level of micropores is increased upon cycling for N-LIG, corresponding to the enhancement of microporous level. Our work successfully develops a novel facile approach to fabricating heteroatom-doped microporous graphene exhibiting high performance and provides new insight into the lithium storage mechanism.

Stimuli-Responsive Materials from Ferrocene-Based Organic Small Molecule for Wearable Sensors

Stimuli-responsive crystals capable of energy conversion have emerged as promising materials for smart sensors, actuators, wearable devices, and robotics. Here, a novel ferrocene-based organic molecule crystal (Fc-Cz) that possesses anisotropic piezoelectric, optical, and mechanical properties is reported. It is demonstrated that the new crystal Fc-Cz can be used as an ultrasensitive piezoelectric material in fabricating strain sensors. The flexible sensor made of crystal Fc-Cz can detect small strains/deformations and motions with a fast response speed. Analysis based on density functional theory (DFT) indicates that an external pressure can affect the dipole moment by changing the molecular configuration of the asymmetric single crystal Fc-Cz in the crystalline state, leading to a change of polarity, and thereby an enhanced dielectric constant. This work demonstrates a new artificial organic small molecule for high-performance tactile sensors, indicating its great potential for developing low-cost flexible wearable sensors.

Small Molecules Derived from Thieno[3,4-c]pyrrole-4,6-dione (TPD) and Their Use in Solution Processed Organic Solar Cells

In this work, microwave synthesis, chemical, optical and electrochemical characterization of three small organic molecules, TPA-TPD, TPA-PT-TPD and TPA-TT-TPD with donor-acceptor structure and their use in organic photovoltaic cells are reported. For the synthesis, 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione was used as electron withdrawing fragment while the triphenylamine was used as electron donating fragment. Molecular electronic geometry and electronic distribution density were established by density functional theory (DFT) calculations and confirmed by optical and chemical characterization. These molecules were employed as electron-donors in the active layer for manufacturing bulk heterojunction organic solar cells, where [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) was used as electron-acceptor. As cathode, Field's metal (FM), an eutectic alloy (Bi/In/Sn: 32.5%, 51%, and 16.5%, respectively) with a melting point above 62 °C, was easily deposited by drop casting under vacuum-free process and at air atmosphere. Prepared devices based on TPA-TPD:PC71BM (1:4 w/w ratio) presented a large VOC = 0.97 V, with JSC = 7.9 mA/cm², a FF = 0.34, then, a power conversion efficiency (PCE) of 2.6%.