Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica Research paper Cyclotriphosphazene cored naphthalimide-BODIPY dendrimeric systems: Synthesis, photophysical and antimicrobial properties Elif Şenkuytu a , Ezel Öztürk a , Fatma Aydınoğlu b , Esra Tanrıverdi Eçik c , Elif Okutan a, ⁎ a Department of Chemistry, Faculty of Science, Gebze Technical University, Gebze, Kocaeli, Turkey b Department of Molecular Biology and Genetics, Faculty of Science, Gebze Technical University, Gebze, Kocaeli, Turkey c Department of Chemistry, Faculty of Science, Atatürk University, Yakutiye, Erzurum, Turkey ARTICLE INFO Keywords: BODIPY Cyclotriphosphazene naphthalimide Photophysical ABSTRACT In this work, we report the synthesis and characterization of novel fluorescent naphthalimide (NI)-boron di- pyrromethene (BODIPY) dyads and dendrimeric triad systems, based on NI functionalized mono- and distyryl- BODIPY derivatives with cyclotriphosphazene core. The structures of new dyads and triad systems were char- acterized by 1 H, 13 C and 31 P NMR. Spectroscopic properties including absorption, emission profiles, fluorescence quantum yield and fluorescence lifetime of NI-BODIPY dyads and NI-BODIPY-cyclotriphosphazene triads were investigated via UV–Vis absorption and fluorescence emission (2D and 3D) techniques. The NI groups on BODIPYs 3- and 5-positions procure the red-shift in absorption and emission spectra compared to BODIPY core. The energy transfer process inhibited the emission of NI moiety and induced the fluorescence from BODIPY unit. The dendrimeric mono- and di-styryl NI-BODIPY-cyclotriphosphazene systems (7 and 8) presented intense ab- sorption bands about 570 and 639 nm respectively both excited from NI and BODIPY subunits. Also, the triad systems (7 and 8) were screened against Gram-positive and Gram-negative bacterial strains. The results de- monstrated that naphthalimide-BODIPY-cyclotriphosphazene triads had an antimicrobial activity against Gram- positive Staphylococcus aureus. 1. Introduction Organic and inorganic ring systems represent prevailing branch of chemistry in which a series of atoms bonded to form varied size ring. Within this family of compounds, the chlorocyclophosphazenes re- ceived maximum attention as inorganic ring system [1–3]. The devel- opment of phosphazene chemistry flourished around nucleophilic sub- stitution reactions and the polymerization of cyclophosphazenes and investigation of properties and potential applications of these con- structions [4]. Especially the ease of the substitution reactions of the chlorines, attached to the phosphorus atoms allow the construction of multimodular systems which can be easily obtained by various nu- cleophiles [5]. It also offers advantageous to utilize in the aimed ap- plication where parameters such as physical and chemical against various influences can be controlled. A wide set of functional groups can be attached to the phosphazene core, allowing many possibilities including further derivatization [6]. These facilities allow the pre- paration of a diverse phosphazene cored dendritic constructs decorated with different fineries such as chromophores (BODIPY, phthalocyanines and perylene etc.) for their photophysical properties [7–9]. Among these chromophores boron-dipyrromethane derivatives (BODIPYs) and naphthalimides (NI) are two of the fluorophores that demonstrate ex- cellent photophysical properties. Therefore, many applications are ac- credited to these molecules, in a vide variety of scientific fields which include biological, molecular imaging, phototheranostics, electro- luminescent devices, construction of organic light emitting diodes (OLED) and photovoltaic cells etc. [10–16]. The ease and wide scope of the modifications around BODIPY core and NIs are made possible aforementioned applications. Especially many studies were focused on the preperation of various NI or BODIPY compounds as potential antimicrobial agents [17–21]. Also the design and preparation of dyad, triad and tetrad type polychromophore sys- tems are popular among scientific community since it provide the op- portunity to use individual properties of the chromophores in a single system [22–24]. Linking of fluorophores in multichromophoric systems can be accomplished via various strategies and connection units can be either aliphatic chains or conjugated moieties. Energy transfer between these systems is crucial for many applications such as solar energy conversion, fluorescent sensors and biological systems in which energy is harvested by one molecular antennae and funnelled to the secondary https://doi.org/10.1016/j.ica.2019.119386 Received 14 November 2019; Received in revised form 17 December 2019; Accepted 17 December 2019 ⁎ Corresponding author. E-mail address: eokutan@gtu.edu.tr (E. Okutan). Inorganica Chimica Acta 502 (2020) 119386 Available online 19 December 2019 0020-1693/ © 2019 Elsevier B.V. All rights reserved. T