Coordination polymers are constructed from metal ions and bridging ligands, linking them into solid-state structures extending in one (1D), two (2D) or three dimensions (3D). Two- and three-dimensional coordination polymers with potential voids are often referred to as metal-organic frameworks (MOFs) or porous coordination polymers. Luminescence is an important property of coordination polymers, often playing a key role in their applications. Photophysical properties of the coordination polymers can be associated with intraligand, metal-centered, guest-centered, metal-to-ligand and ligand-to-metal electron transitions. In recent years, a rapid growth of publications devoted to luminescent or fluorescent coordination polymers can be observed. In this review the use of fluorescent ligands, namely, 4,4′-stilbenedicarboxylic acid, 1,3,4-oxadiazole, thiazole, 2,1,3-benzothiadiazole, terpyridine and carbazole derivatives, naphthalene diimides, 4,4′,4′′-nitrilotribenzoic acid, ruthenium(II) and iridium(III) complexes, boron-dipyrromethene (BODIPY) derivatives, porphyrins, for the construction of coordination polymers are surveyed. Applications of such coordination polymers based on their photophysical properties will be discussed. The review covers the literature published before April 2020.

Adipose tissue exhibits dynamic metabolic and structural changes in response to environmental stimuli, including temperature fluctuations. While continuous cold exposure has been extensively studied, the molecular effects of prolonged intermittent cold exposure (ICE) remain poorly characterized. Here, we present a proteomic analysis of inguinal white adipose tissue (IWAT) from mice subjected to a 16-week regimen of short-term daily ICE (6 °C for 6 h, 5 days per week) without compensatory caloric intake. Mass spectrometry identified 1108 proteins, with 140 differentially expressed between experimental and control groups. ICE significantly upregulated mitochondrial proteins associated with lipid and carbohydrate catabolism, the tricarboxylic acid (TCA) cycle, oxidative phosphorylation, and lipogenesis, including LETM1, AIFM1, PHB, PHB2, ACOT2, NDUA9, and ATP5J. These changes reflect enhanced metabolic activity and mitochondrial remodeling. In contrast, proteins linked to oxidative stress, insulin resistance, inflammation, and extracellular matrix remodeling were downregulated, such as HMGB1, FETUA, SERPH1, RPN1, and AOC3. Notably, gamma-synuclein (SYUG), which inhibits lipolysis, was undetectable in ICE-treated samples. Our findings support the hypothesis that ICE promotes thermogenic reprogramming and metabolic rejuvenation in subcutaneous fat through activation of futile cycles and mitochondrial restructuring. This study offers molecular insights into adaptive thermogenesis and presents intermittent cold exposure as a potential strategy to mitigate adipose tissue aging.

Mitochondrial uncoupling protein (UCP1) facilitates adaptive non-shivering thermogenesis in brown and beige adipocytes due to uncoupling of mitochondrial respiration and oxidative phosphorylation (ATP synthesis). The presence of UCP1-expressing adipocytes in fat depots is known to promote metabolic health and provide protection against metabolic disorders, thus stimulating interest in studying the age-related dynamics of UCP1 expression. The available data are scarce and were mainly obtained on obesity-prone C57Bl/6J mice, referring to either early or late ontogenesis. In our study, UCP1 expression in adipose tissues of outbred male ICR mice was studied for the first time in the period from weaning to old age. Interscapular brown adipose tissue (BAT), as well as inguinal and perigonadal white adipose tissues (IWAT and GWAT, respectively), were sampled from mice aged 20 days, 1.5, 6, and 18 months. UCP1 expression levels were assessed by Western blotting. In IWAT, relative UCP1 expression decreased 2-fold between the ages of 20 days and 1.5 months, and was undetectable at later stages. In GWAT, UCP1 expression was only detected in 30% of the tissue samples from mice aged between 1.5 and 6 months, with its level being 10-fold lower compared to IWAT depots. In BAT, no statistically significant changes in UCP1 expression were revealed. The physiological role of the UCP1-expressing cell population in GWAT, as well as a possible relationship between UCP1 expression time course and decline rate during the growth and maturation of reproductive function and the activation of lipogenesis in IWAT, are discussed.

Uncoupling protein (UCP1) uncouples mitochondrial respiration from ATP synthesis, resulting in heat production in brown and beige adipocytes. The presence of adipocytes with UCP1 expression in fat depots has been shown to promote metabolic health and provide protection against metabolic disorders. It stimulates interest in studying the age dynamics of UCP1 expression. There are few data available, mainly obtained on the C57Bl/6J mouse line predisposed to obesity and cover either early or late ontogenesis. In our study, for the first time, the expression of the UCP1 protein in the adipose tissues of male ICR mice was studied from the weaning to old age. Interscapular brown adipose tissue (BAT), inguinal and perigonadal white adipose tissue (IWAT and GWAT) of 20-day, 1.5, 6, 18 months mice were collected. UCP1 levels were detected by western-blotting. IWAT UCP1 expression decreased by 2 times between 20 days and 1.5 months. No UCP1 bands on blots from mice older than 1.5 months were observed. In gonadal depot UCP1 was detected only in 30% of the samples from 1.5- and 6‑months old mice, and UCP1 expression level was ten times lower in compare to inguinal depot. No statistically significant changes in UCP1 protein expression were detected in brown adipose tissue. The physiological role of UCP1-expressing cells in GWAT is discussed, as well as a possible relationship between the timing and rate of UCP1 expression decrease during the growth and maturation of reproductive function with the activation of lipogenesis in inguinal adipose tissue.