A polydentate ligand based on 2,2’-dipyridylamine unit linked benzo-15-crown-5; alkali and transition metal complexes; photoresponsive ligand; antimicrobial evaluation against pathogenic microorganisms

Abstract

New double-armed benzo-15-crown-5 compound (L) was successfully synthesized from 4’,5’-bis(bromethyl)benzo-15-crown-5 with 2,2’-dipyridylamine. The synthesized host molecule (L), the dipyridylamine unit was able to coordinate Ni²⁺, Cu²⁺ and Ag⁺ metal cations, whereas the crown ether moiety bound with the alkali metal cations (Na⁺ and K⁺). The structures of the ligand (L), alkali metal complexes (NaL and KL2) and transition metal complexes ([NiLOAc], [CuLOAc] and [AgLNO3]) were characterized by spectroscopic methods. NMR and mass data provided exact evidence of complex formation through both coordination centers of the new ligand (L). Both parts (dipyridyl and crown ether) were linked to form a potential fluorescent-sensing compound (L) for metal cations. Therefore, to investigate the metal selectivity, different metal cations (Na⁺, Mg²⁺, K⁺, Ba²⁺, Cr³⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Ag⁺) and the new sensing compound (L) fluorescence spectra were recorded. Coordinations with Zn²⁺, Fe³⁺ and Cu²⁺ induced obvious changes on their increasing concentrations in fluorescence spectra. Crown ethers, as representatives of supramolecular compounds, are also promising antibacterial active compounds because of their ionophoric features. Synthesized ligand (L) and complexes (NaL, KL2, [NiLOAc], [CuLOAc] and [AgLNO3]) also proved to be adjuvants that helped to overcome antimicrobial resistance in a range of bacteria and yeast. The antimicrobial activity of compounds was screened in vitro against some pathogenic Gram-positive bacteria, some Gram-negative bacteria and yeast.

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Transition Metal Chemistry (2021) 46:509–522
https://doi.org/10.1007/s11243-021-00469-1
A polydentate ligand based on2,2’‑dipyridylamine unit linked
benzo‑15‑crown‑5; alkali andtransition metal complexes;
photoresponsive ligand; antimicrobial evaluation againstpathogenic
microorganisms
SerhatKoçoğlu1,2 · ZelihaHayvalı2· HaticeOgutcu3
Received: 21 March 2021 / Accepted: 22 June 2021 / Published online: 30 June 2021
© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2021
Abstract
New double-armed benzo-15-crown-5 compound (L) was successfully synthesized from 4’,5’-bis(bromethyl)benzo-15-
crown-5 with 2,2’-dipyridylamine. The synthesized host molecule (L), the dipyridylamine unit was able to coordinate
Ni2+, Cu2+ and Ag+ metal cations, whereas the crown ether moiety bound with the alkali metal cations (Na+ and K+). The
structures of the ligand (L), alkali metal complexes (NaL and KL2) and transition metal complexes ([NiLOAc], [CuLOAc]
and [AgLNO3]) were characterized by spectroscopic methods. NMR and mass data provided exact evidence of complex
formation through both coordination centers of the new ligand (L). Both parts (dipyridyl and crown ether) were linked to
form a potential fluorescent-sensing compound (L) for metal cations. Therefore, to investigate the metal selectivity, differ-
ent metal cations (Na+, Mg2+, K+, Ba2+, Cr3+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+ and Ag+) and the new sensing compound (L)
fluorescence spectra were recorded. Coordinations with Zn2+, Fe3+ and Cu2+ induced obvious changes on their increasing
concentrations in fluorescence spectra. Crown ethers, as representatives of supramolecular compounds, are also promising
antibacterial active compounds because of their ionophoric features. Synthesized ligand (L) and complexes (NaL, KL2,
[NiLOAc], [CuLOAc] and [AgLNO3]) also proved to be adjuvants that helped to overcome antimicrobial resistance in a
range of bacteria and yeast. The antimicrobial activity of compounds was screened invitro against some pathogenic Gram-
positive bacteria, some Gram-negative bacteria and yeast.
Introduction
Crown ether ligands have been extensively studied since
their discovery by Pedersen in 1967 and have been used
as cation binding subunits in various receptors [1, 2]. They
have selectivity for a particular metal cation according to
their particular molecular structure. From this perspective,
crown ethers have been extensively studied as a host–guest
recognition unit in a variety of receptors and applications
due to their size differences and strong affinity for metal
ions [2, 3]. Armed crown ethers are particularly interest-
ing molecules in supramolecular chemistry. Ditopic crown
ethers having binding site for both cation species (alkali and
transition) have to be designed to overcome more challenges
than just simple metal ion receptors [4].
2,2′-Dipyridylamine is widely used in organometallic
and inorganic chemistry as amultidentate ligand [4–6].
The coordination ability of 2,2′-dipyridylamine has been
the subject of many studies reflecting its affinity for a num-
ber of transition metal ions [7, 8]. Pd2+ and Pt2+ complexes
of 2,2′-dipyridylamine and its derivatives have also been
investigated as potential anticancer agents due to their
structural similarities to cis-platin [9]. A number of new
dipyridylamine ligands have been used in studies ranging
from cation coordination and supramolecular compounds to
thesynthesis of new luminescent compounds [6].
In this work we present the synthesis of symmetri-
cal 2,2′-dipyridyl substituted benzo-15-crown-5 core
(Scheme1). This compound with multiple binding sites has
* Serhat Koçoğlu
serhatkocoglu@baskent.edu.tr
1 Food Processing Department, Kahramankazan Vocational
School, Başkent University, 06980Ankara, Turkey
2 Department ofChemistry, Faculty ofScience, Ankara
University, 06100Ankara, Turkey
3 Department ofField Crops, Faculty ofAgriculture, Kırşehir
Ahi Evran University, 40100Kırşehir, Turkey
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