Modified Triphenylmethane-based Polyimides with Improved Optical,Dielectric and Solubility Properties via Post-Polymerization Modification

A family of new triphenylmethane(TPM)-based polyimides(PIs)containing bulky tert-butyldimethylsiloxy(TBS)side-groups(PI-TPMOSis)has been prepared by a post-polymerization modification via a simple silyl ether reaction of TPM-based PIs containing hydroxyl(OH)groups(PI-TPMOHs).The attachment of TBS side-groups in PI-TPMOSis can be achieved up to 100%,as confirmed by the 1H-NMR and IR spectra.Due to the presence of the TPM structure,PI-TPMOSi films still display the excellent thermal stability with high glass transition temperature(Tg)of 314–351°C and high degradation temperature(Td5%)of 480–501°C.It is quite remarkable that the introduction of TBS side-groups into PI-TPMOSi chains results in more superior optical,dielectric and solubility properties in comparison with the precursor PI-TPMOH films,probably due to the reductions of the packing density and charge-transfer complexes(CTCs)formation.The optical transmittance at 400 nm(T400)of PI-TPMOSi films is significantly increased from 45.3%–68.8%to 75.4%–81.6%of the precursor PI-TPMOH films.The dielectric constant(Dk)and dissipation factor(Df)at 1 MHz of PI-TPMOSi films are reduced from 4.11–4.40 and 0.00159–0.00235 to 2.61–2.92 and 0.00125–0.00171 of the precursor PI-TPMOH films,respectively.Combining the molecular design and simple preparation method,this study provides an effective approach for enhancement of various properties of PI films for microelectronic and photoelectric engineering applications.

Endogenous formaldehyde responsive fluorescent probe for bioimaging

Formaldehyde(FA),as the simplest endogenous carbonyl molecule,participates in many biosynthesis and metabolism in living organisms,such as nucleotides and adenosine triphosphate(ATP).FA concentrations are sub-millimolar in the normal healthy body,but can rise significantly in a number of disease pathologies.As a result,detecting endogenous FA is critical for illness diagnosis and rehabilitation therapy monitoring.Recent studies have focused on the FA-responsive turn-on fluorescence probe,which has huge promise in the detection and visualization of FA in living cells and organisms,as well as exceptional use in disease diagnosis and therapeutic monitoring.This review summarizes the fluorescence luminescence mechanism and design concepts of FA fluorescent probes,as well as their recent applications in bioimaging and illness diagnostics.Additionally,this article indicates the present dilemma of FA-responsive fluorescent probe,including selectivity,specificity,and detection mode,which may provide references for the development of FA-responsive fluorescent probes.