The Sonogashira reaction is a cross-coupling reaction of a vinyl or aryl halide with a terminal alkyne to form a C–C bond. In its original form, the Sonogashira reaction is performed with a palladium species as a catalyst while co-catalyzed by a copper species and a phosphine or amine. The reaction is conducted under mild conditions, i.e., room temperature, aqueous solutions, and the presence of mild bases. Undeniably, the Sonogashira reaction is among the most competent and efficient reactions widely used in organic synthesis. This named reaction has proved useful in many organic synthesis areas, including the synthesis of pharmaceuticals, heterocycles, natural products, organic compounds, complex molecules having biological activities, nanomaterials, and many more materials that we use in our daily lives. The presence of transition metals as a catalyst was indeed essential in the Sonogashira reaction. However, recently, the reaction has been successfully conducted without copper as a co-catalyst and phosphines or amines as bases. In this critical review, we have focused on developments in the Sonogashira reaction successfully performed in the absence of copper complexes, phosphines or amines, which could be of particular advantage in implementing green chemistry principles and making the reactions more achievable from an economic viewpoint.

Today, MXenes and their composites have shown attractive capabilities in numerous fields of electronics, co-catalysis/photocatalysis, sensing/imaging, batteries/supercapacitors, electromagnetic interference (EMI) shielding, tissue engineering/regenerative medicine, drug delivery, cancer theranostics, and soft robotics. In this aspect, MXene-carbon nanotube (CNT) composites have been widely constructed with improved environmental stability, excellent electrical conductivity, and robust mechanical properties, providing great opportunities for designing modern and intelligent systems with diagnostic/therapeutic, electronic, and environmental applications. MXenes with unique architectures, large specific surface areas, ease of functionalization, and high electrical conductivity have been employed for hybridization with CNTs with superb heat conductivity, electrical conductivity, and fascinating mechanical features. However, most of the studies have centered around their electronic, EMI shielding, catalytic, and sensing applications; thus, the need for research on biomedical and diagnostic/therapeutic applications of these materials ought to be given more attention. The photothermal conversion efficiency, selectivity/sensitivity, environmental stability/recyclability, biocompatibility/toxicity, long-term biosafety, stimuli-responsiveness features, and clinical translation studies are among the most crucial research aspects that still need to be comprehensively investigated. Although limited explorations have focused on MXene-CNT composites, future studies should be planned on the optimization of reaction/synthesis conditions, surface functionalization, and toxicological evaluations. Herein, most recent advancements pertaining to the applications of MXene-CNT composites in sensing, catalysis, supercapacitors/batteries, EMI shielding, water treatment/pollutants removal are highlighted, focusing on current trends, challenges, and future outlooks.

MXenes with unique mechanical, optical, electronic, and thermal properties along with a specific large surface area for surface functionalization/modification, high electrical conductivity, magnetic properties, biocompatibility, and low toxicity have been explored as attractive candidates for the targeted delivery of drugs in cancer therapy. These two-dimensional materials have garnered much attention in the field of cancer therapy since they have shown suitable photothermal effects, biocompatibility, and luminescence properties. However, outstanding challenging issues regarding their pharmacokinetics, biosafety, targeting properties, optimized functionalization, synthesis/reaction conditions, and clinical translational studies still need to be addressed. Herein, recent advances and upcoming challenges in the design of advanced targeted drug delivery micro- and nanosystems in cancer therapy using MXenes have been discussed to motivate researchers to further investigate this field of science.

Covalent organic frameworks (COFs) are crystal-like organic structures such as cartography buildings prepared from appropriately pre-designed construction block precursors. Moreover, after the expansion of the first COF in 2005, numerous researchers have been developing different materials for versatile applications such as sensing/imaging, cancer theranostics, drug delivery, tissue engineering, wound healing, and antimicrobials. COFs have harmonious pore size, enduring porosity, thermal stability, and low density. In addition, a wide variety of functional groups could be implanted during their construction to provide desired constituents, including antibodies and enzymes. The reticular organic frameworks comprising porous hybrid materials connected via a covalent bond have been studied for improving wound healing and dressing applications due to their long-standing antibacterial properties. Several COF-based systems have been planned for controlled drug delivery with wound healing purposes, targeting drugs to efficiently inhibit the growth of pathogenic microorganisms at the wound spot. In addition, COFs can be deployed for combinational therapy using photodynamic and photothermal antibacterial therapy along with drug delivery for healing chronic wounds and bacterial infections. Herein, the most recent advancements pertaining to the applications of COF-based systems against bacterial infections and for wound healing are considered, concentrating on challenges and future guidelines.