Luminescence Properties of Self-Aggregating TbIII-DOTA-Functionalized Calix[4]arenes

Abstract

Self-aggregating calix[4]arenes carrying four DOTA ligands on the upper rim for stable complexation of paramagnetic GdIII-ions have already been proposed as MRI probes. In this work, we investigate the luminescence properties of TbIII-DOTA-calix[4]arene-4OPr containing four propyl-groups and compare them with those of the analog substituted with a phthalimide chromophore (TbIII-DOTA-calix[4]arene-3OPr-OPhth). We show that, given its four aromatic rings, the calix[4]arene core acts as an effective sensitizer of Tb-centered luminescence. Substituents on the lower rim can modulate the aggregation behavior, which in turn determines the luminescence properties of the compounds. In solid state, the quantum yield of the phthalimide derivative is almost three times as high as that of the propyl-functionalized analog demonstrating a beneficial role of the chromophore on Tb-luminescence. In solution, however, the effect of the phthalimide group vanishes, which we attribute to the large distance between the chromophore and the lanthanide, situated on the opposite rims of the calix[4]arene. Both quantum yields and luminescence lifetimes show clear concentration dependence in solution, related to the strong impact of aggregation on the luminescence behavior. We also evidence the variability in the values of the critical micelle concentration depending on the experimental technique. Such luminescent calix[4]arene platforms accommodating stable lanthanide complexes can be considered valuable building blocks for the design of dual MR/optical imaging probes.

Alteration of metabolic profiles in Lemna paucicostata culture and enhanced production of GABA and ferulic acid by ethephon treatment

“…Ethylene is a well-known plant hormone that regulates cell growth, reproduction, senescence, and various metabolites production in plants [5,6]; interestingly, unlike any other plant hormone, ethylene is a gas. Previous studies have shown that 1-amino cyclopropane-1-carboxylic acid, a precursor of ethylene, reduced growth and fresh weight but increased the chlorophyll content of Lemna minor [7]. Furthermore, ethylene resulted in fast underwater elongation of Oryza sativa and Rumex palustris [8].…”

“…Depending on plant species, tissue type, and ethylene concentration, ethylene affects growth, number, or plant size differently [27]. Thus, for example, in some hydrophytes such as rice, ethylene accelerates growth, whereas in others, such as Lemna minor, it hampers growth [7,28]. A previous study showed that ethephon treatment increased the total number of corms without changing the total weight of potted Freesia [13].…”

A Facile Method for the Non-Covalent Amine Functionalization of Carbon-Based Surfaces for Use in Biosensor Development

“…Another example of an aromatic amine compound used in biosensor development is 1,5-diaminonaphthalene (DAN) which has been previously used for the electrochemical detection of chloramphenicol using edge plane pyrolytic graphite sensors [ 24 ] and the detection of sulfamethoxazole using glassy carbon electrodes [ 25 ]. However DAN has also been realized as a functionalization method for use in GFET or resistor based sensors, for example in the detection of Hg 2+ [ 26 ] or for hydrogen gas sensing [ 27 ]. Much research into the use of DAN for graphene functionalization has been demonstrated when utilized in its polymeric form (pDAN), for the creation of thin conducting films on top of the graphene surface for sensing purposes, including the use of pDAN films to improve enzymatic electrochemical sensing [ 28 ] and for the detection of lactose [ 29 ].…”

Impact of Thermal Treatment of Nb2O5 on Its Performance in Glucose Dehydration to 5-Hydroxymethylfurfural in Water

“…The efficient utilization of lignocellulosic biomass is essential for building a sustainable society. In this respect, cellulose can be converted into glucose via a combination of mechanical treatment and acid-catalyzed hydrolysis [ 1 , 2 , 3 ]. Subsequently, as-obtained glucose can be further transformed into biofuel precursors [ 4 , 5 ], commodity chemicals [ 6 ], or other important platform molecules such as 5-hydroxymethylfurfural (HMF).…”