A new metal ion sensor that contains quinoline and pyridylaminophenol has been synthesized. In acetonitrile and in the presence of Zn²⁺, the sensor fluoresces. In contrast, in aqueous solutions the sensor fluoresces in the presence of Cd²⁺. The fluorescence of the molecule is selective for Zn²⁺ or Cd²⁺ and shows no fluorescence with other metal ions. The crystal structure of the Cd²⁺ complex shows coordination through the amide and phenol oxygens, as well as the amine nitrogen of the sensor. The sensor also acts as a colorimetric sensor for Co²⁺ by changing color from colorless to yellow. The color change is selective for Co²⁺ and is not observed with other metal ions. The unique combination of pyridine and phenol groups with quinoline results in the properties of this sensor.

Zinc sensors based on 2,3-dipicolylamine (DPA) and quinoline have been synthesized. They fluoresced in the presence of Zn²⁺ and remained fluorescent when other metal ions were present. Fluorescence enhancement of the sensors was not seen for most other metal ions. In vitro studies with fibroblasts showed fluorescence when sensor and Zn²⁺ were present. As seen by single crystal X-ray analysis, four nitrogens from the sensor bind to Zn²⁺. These new sensors have lower binding constants than the pentadentate sensors based on 2,2-DPA.

Iminodiacetate resorc[4]arene is shown to produce gels that are pH-reversible. The gels formed are clear and stable to inversion. (The gels are not stable above a certain temperature, which varies with concentration.) When the pH of an iminodiacetate resorc[4]arene solution (concentration >7.6 mM) is lowered to below 2.5, which is near one of the K_a values of the molecule, the dissolved molecules aggregate and cause gelation of water. ¹H NMR showed that at the pH of gelation a change occurs in the chemical environment of the iminodiacetate group. Scanning electron microscopy showed that the gel is composed of long strands that interweave and create a molecular mesh.

Polyimide composites represent a class of advanced materials with remarkable mechanical robustness and thermal stability, making them highly suitable for applications in extreme environments. Their unique ability to maintain performance under high temperatures and corrosive conditions, combined with a favorable strength-to-weight ratio, positions them as critical components in aerospace, electronics, and automotive systems. Several leading aerospace and electronics corporations have made significant investments in incorporating polyimide composites into their products, indicating the material’s transformative potential. This review paper provides an overview of mechanical and thermal behaviors of polyimide composites, summarizing recent developments and research trends. It examines the influence of various reinforcements, processing techniques, and composite architectures on material performance under mechanical loading and thermal stress. The paper synthesizes findings from experimental studies and modeling efforts to highlight the critical factors affecting strength, durability, and thermal stability. Discussion and recommendations regarding applications in aerospace, electronics, and other high-temperature environments are provided, emphasizing the challenges and opportunities presented by these advanced materials. This review adopts a broad scope to reflect the interdisciplinary nature of polyimide research. Due to gaps in literature, this work aims to provide a foundational overview that supports future, more specialized investigations.