Engineering a light-driven cyanine based molecular rotor to enhance the sensitivity towards a viscous medium.

This article describes the enhanced sensitivity to a viscous medium by a molecular rotor based fluorophore (RBF), TPSI I. The TPSI I molecule is designed in such a way that it consists of a rotor and a fluorophore with a p-rich bridge between them. TPSI I is a light-responsive material in solution as well as in the solid state. The structural design of the molecule allows flexible rotation and photo-induced cis-trans isomerization both in the solid state as well as in solution. These combined attributes of TPSI I are responsible for the ultrasensitive viscosity response of the new material, which was verified through the Fo ̈rster-Hoffmann equation. According to this equation, the derived 'x' value is 1.02 (x is related to the sensitivity) which is the highest among the contemporary reports for RBFs. The facts were evidenced both by experimental as well as theoretical data. The ultrasensitivity towards viscosity was further analyzed in in vitro studies by detecting the subtle changes in the alteration of intracellular viscosity in normal and cancerous cells. An alteration of intracellular viscosity in cells treated with viscosity modula- tors was also confirmed using a previously well-established viscosity measurement technique, dynamic measurement through the piezoelectric patch. Our research offers a detailed mechanism to improve viscosity sensors and an efficient probe for detecting minute changes in intracellular viscosity

Stimuli-responsive electrospun fluorescent fibers augmented with aggregation-induced emission (AIE) for smart applications

This review addresses the latest advancements in the integration of aggregation-induced emission (AIE) materials with polymer electrospinning, to accomplish fine-scale electrospun fibers with tunable photophysical and photochemical properties. Micro- and nanoscale fibers augmented with AIE dyes (termed AIEgens) are bespoke composite systems that can overcome the limitation posed by aggregation-caused quenching, a critical deficiency of conventional luminescent materials. This review comprises three parts. First, the reader is exposed to the basic concepts of AIE and the fundamental mechanisms underpinning the restriction of intermolecular motions. This is followed by an introduction to electrospinning techniques pertinent to AIE-based fibers, and the core parameters for controlling fiber architecture and resultant properties. Second, exemplars are drawn from latest research to demonstrate how electrospun nanofibers and porous films incorporating modified AIEgens (especially tetraphenylethylene and triphenylamine derivatives) can yield enhanced photostability, photothermal properties, photoefficiency (quantum yield), and improved device sensitivity. Advanced applications are drawn from several promising sectors, encompassing optoelectronics, drug delivery and biology, chemosensors and mechanochromic sensors, and innovative photothermal devices, among others. Finally, the outstanding challenges together with potential opportunities in the nascent field of electrospun AIE-active fibers are presented, for stimulating frontier research and explorations in this exciting field

Tailored Broad-Spectrum Emission in Hybrid Aggregation Induced Emission (AIE)-MOFs: Boosting White Light Efficiency in Electrospun Janus Microfibers

Advances in energy-efficient lighting and display technologies demand innovative materials with tailored broad-spectrum emission properties. Hybrid aggregation-induced emission metal-organic frameworks (AIE-MOFs) offer a promising avenue, combining unique characteristics of organic and inorganic components to yield enhanced lumi-nescence efficiency and robust material stability. Our study introduces a spectrum of D (donor)-A (acceptor) type AIE-active ligands into MOFs, enabling tunable emission across the visible spectrum, thus underscoring the versatility of these hybridized MOF materials. We further harness the emission properties of AIE-MOFs by integrating them into polymer matrices, resulting in high-performance electrospun fibers with tunable emission. A significant achievement involves the fabrication of Janus-type white light-emitting AIE-MOF fiber composites via side-by-side electrospinning, accomplishing a high quantum yield of 58%, which doubled the performance of homogeneous fibers. Complement-ing our experimental findings, we employ micro-Raman and nano-FTIR as local spectroscopic probes, affording a deeper understanding of the material properties and the mechanisms contributing to enhanced light emission. In our understanding, this study presents an unconventional implementation of hybrid AIE-MOFs in Janus-type structures for white light emission. It significantly improves the efficiency of white light sources in optoelectronics, charting a promising direction for future research in the emergent AIE-MOF field

‘Aggregation-Induced Emission’ Active Mono-Cyclometalated Iridium(III) Complex Mediated Efficient Vapor-Phase Detection of Dichloromethane

Selective vapor-phase detection of dichloromethane (DCM) is a challenge, it being a well-known hazardous volatile organic solvent in trace amounts. With this in mind, we have developed an ‘Aggregation-induced Emission’ (AIE) active mono-cyclometalated iridium(III)-based (M1) probe molecule, which detects DCM sensitively and selectively in vapor phase with a response time <30 s. It reveals a turn-on emission (non-emissive to intense yellow) on exposing DCM vapor directly to the solid M1. The recorded detection limit is 4.9 ppm for DCM vapor with pristine M1. The mechanism of DCM detection was explored. Moreover, the detection of DCM vapor by M1 was extended with a low-cost filter paper as the substrate. The DCM is weakly bound with the probe and can be removed with a mild treatment, so, notably, the probe can be reused

Strategic design and synthesis of AIEE (Aggregation Induced Enhanced Emission) active push-pull type pyrene derivatives for the ultrasensitive detection of explosives

Tuning of solid and solution phase emission with simple push-pull ‘Aggregation Induced Enhanced Emission’ (AIEE) pyrene compounds for deeper understanding on the mechanism for selectivity and sensitivity towards the nitro explosives with lowering the detection limit upto ppt (parts per trillion) level. Keywords: AIEE 1, Ultrasensitive explosive detection 2, Photo induced electron transfer and energy mechanism

Achieving Single-Component Solid-State White-Light Emission through Polymerization-Induced Phosphorescent Emission

The non-luminescent monomeric unit M1 transforms into intensely yellow emissive phosphorescent polymers upon polymerization, termed polymerization-induced phosphorescent emission (PIPE). A simple free radical polymerization method is employed for the polymer synthesis where the homopolymer (HP) exhibiting PIPE is generated from vinyl monomers (M1) via non-conjugated bond formation. High photo efficiency observed for the PIPE-active HP may have resulted from the possible intrachain and interchain interactions, among the repeating units. By using various monomer compositions, this synthetic technique provides copolymer and emission tuning. Integrating blue-emitting carbazole with the PIPE-active HP resulted in the white-light-emitting copolymer (CP4). This is the first report on PIPE-active-mediated white-light-emitting copolymer with CIE coordinates (0.25, 0.33). The resulting copolymer (CP4) showed a high quantum yield (33.7%) with a long excited-state lifetime (6.54 μs). PIPE-active phosphorescent-based white-light-emissive polymeric materials could motivate the development of advanced materials for white-light-emitting diode devices

Unlocking diabetic acetone vapor detection by a portable metal-organic framework-based optical sensor device

Despite exhaled human breath having enabled noninvasive diabetes diagnosis, selective acetone vapor detection by fluorescence approach in the diabetic range (1.8-3.5 ppm) remains a long-standing challenge. We report a set of water-resistant luminescent metal-organic framework (MOF)-based composites for detecting acetone vapor in the diabetic range with a limit of detection of 200 ppb. The luminescent materials can also detect acetone vapor selectively unimpeded by excessive water vapor and other competing VOCs mixture, and it can be reused in minutes under ambient conditions. Industrially pertinent electrospun unique luminescent fibers were likewise fabricated alongside various luminescent films for selective detection of ultratrace quantities of acetone vapor present in the air. Ab initio theoretical calculations combined with in situ synchrotron-based dosing studies uncovered the material’s remarkable hypersensitivity towards acetone vapor. Finally, a freshly designed prototype fluorescence-based portable optical sensor was utilized for the rapid detection of acetone vapor within the diabetic range

Nanoconfinement of tetraphenylethylene in zeolitic metal-organic framework for turn-on mechanofluorochromic stress sensing

Mechanofluorochromic materials are of great significance for the fabrication of innovative sensors and optoelectronics. However, efficient mechanofluorochromic materials are rarely explored due to the deficiency of existing design strategies. Here, we demonstrate the incarceration of aggregation-induced emission (AIE) materials within metal-organic framework (MOF) single crystals to construct a composite system with turn-on mechanofluorochromism. A new type of AIE@MOF material was designed: integrating a zeolitic MOF (ZIF-71) and tetraphenylethylene (TPE, a topical AIE material) to generate a TPE@ZIF-71 system with exceptional turn-on type mechanofluorochromism. Using terahertz vibrational spectroscopy, we show the unique fluorochromism mainly emanates from the enhanced nanoconfinement effect exerted by ZIF-71 host on TPE guest under pressure. Compared with pure TPE, we demonstrate the nanoconfinement in AIE@MOF not only changes the TPE's turn-off type sensing behavior to a turn-on type, but boosts the original sensitivity markedly by tenfold. Significantly, because ZIF-71 prevents the spontaneous recrystallization of TPE upon unloading, this allows TPE@ZIF-71 to record the stress history. This is the first demonstration of the Guest@MOF system combining the concepts of AIE and MOF; its promising properties and potential engineering applications will stimulate new directions pertaining to luminescent stress sensors and smart optics

Unlocking Diabetic Acetone Vapor Detection by A Portable Metal‐Organic Framework‐Based Turn‐On Optical Sensor Device

Abstract Despite exhaled human breath having enabled noninvasive diabetes diagnosis, selective acetone vapor detection by fluorescence approach in the diabetic range (1.8–3.5 ppm) remains a long‐standing challenge. A set of water‐resistant luminescent metal‐organic framework (MOF)‐based composites have been reported for detecting acetone vapor in the diabetic range with a limit of detection of 200 ppb. The luminescent materials possess the ability to selectively detect acetone vapor from a mixture comprising nitrogen, oxygen, carbon dioxide, water vapor, and alcohol vapor, which are prevalent in exhaled breath. It is noteworthy that this is the first luminescent MOF material capable of selectively detecting acetone vapor in the diabetic range via a turn‐on mechanism. The material can be reused within a matter of minutes under ambient conditions. Industrially pertinent electrospun luminescent fibers are likewise fabricated alongside various luminescent films for selective detection of ultratrace quantities of acetone vapor present in the air. Ab initio theoretical calculations combined with in situ synchrotron‐based dosing studies uncovered the material's remarkable hypersensitivity toward acetone vapor. Finally, a freshly designed prototype fluorescence‐based portable optical sensor is utilized as a proof‐of‐concept for the rapid detection of acetone vapor within the diabetic range