A new Cu2+-induced color reaction of a rhodamine derivative N-(3-carboxy)acryloyl rhodamine B hydrazide

Abstract

A new rhodamine derivative, N-(3-carboxy)acryloyl rhodamine B hydrazide (CARB), has been synthesized, and its unusual spectroscopic reaction with Cu 2+ has been investigated. The derivative exhibits a rapid and reversible non-fluorescent absorption upon coordination to Cu 2+ , which is a rather unusual phenomenon for rhodamine B derivatives. Stoichiometric measurements using the Job's method and the molar ratio method reveal that one CARB molecule combines two Cu 2+ ions, and the two Cu 2+ ions play different roles: one opens the spirocyclic structure and the other quenches the fluorescence of the xanthene moiety. This reaction mechanism is supported by a comparative study on the model compound N-acryloyl rhodamine B hydrazide as well as by the density functional theory calculations. Furthermore, the absorption response of CARB is highly selective for Cu 2+ over other common ions, which implies that CARB may be used as a colorimetric probe for the rapid visual detection of Cu 2+ .

Effects of Single and Double Bonds in Linkers on Colorimetric and Fluorescent Sensing Properties of Polyving Akohol Grafting Rhodamine Hydrazides

“…Synthesis of N-Mono-Maleic Acid Amide-N′-Rhodamine B Hydrazide (MRBH) and N-Mono-Succinic Acid Amide-N ′-Rhodamine 6G Hydrazide (SR6GH) N-mono-maleic acid amide-N′-rhodamine B hydrazide (MRBH) were prepared according to literature protocol [3,27,28]. Briefly, rhodamine B hydrazide (RBH) (0.4566 g, 1.0 mmol) was dissolved in dichloromethane (30 mL), to which a solution of maleic anhydride (MAH) (0.1975 g, 1.0 mmol) in dichloromethane (10 mL) was added dropwise.…”

“…Development of chemosensors for sensing and recognition of environmentally and biologically important heavy and transition metal ions, for example, Hg 2+ , Cu 2+ , Fe 3+ and Cr 3+ , have attracted considerable attention of current researchers [1][2][3][4][5][6][7][8][9]. Fluorescent chemosensors provide several advantages over other analytical methods, such as high sensitivity, specificity, convenience, real time monitoring with fast response times, and low cost [10].…”

“…They have been widely used as a molecular platform for the design of new spectroscopic probes [3,10]. Moreover, in the absence of cations, these rhodamine-based chemosensors exist in a spirocyclic form, which is colorless and non-fluorescent.…”

“…The addition of a specific metal ion leads to spirocycle unit opening via coordination or irreversible chemical reaction, resulting in the appearance of a pink color Electronic supplementary material The online version of this article (doi:10.1007/s10895-015-1528-y) contains supplementary material, which is available to authorized users. or orange fluorescence [3,6,15]. Thereby, the rhodamine fluorophore can be an ideal framework to construct off-on system for the specific metal ion [8].…”

“…Up to now, variety of chemosensors for metal ions have been fabricated from small organic molecules based rhodamine derivataves [3]. However, most of these small molecular chemosensors typically exhibit poor water solubility, which partially limits their practical applications in diverse fields [4,11].…”