Synthesis and Studies on Photophysical Properties of Rhodamine Derivatives for Bioimaging Applications

Abstract

Rhodamine derivatives have been persistently used as fluorescent/solvatochromic dyes in various areas. For example, they are used as a labeling agent in biotechnology and a chemosensor. Also, rhodamine derivatives are used for cell imaging experiment. Herein, we report on the synthesis of fluorescent derivatives based on rhodamine B (RHB1, RHB2, and RHB3). We confirmed the structures and purities of the synthesized probes i.e., RHB1, RHB2, and RHB3 by using analytical technique's viz. 1 H NMR, 13 C NMR, Mass and FT-IR followed by exploring spectroscopic properties by using fluorescence/UV absorption spectroscopy. The effect of solvents on the fluorescence and absorption properties of the synthesized compounds has been comprehensively studied using a series of solvent. In addition, synthesized RHB1, RHB2, and RHB3 were found to be non-toxic against the cancer cell (MDA-MB-231). It is clear from the result of the conventional fluorescence microscopy that probe RHB2 exhibits significant optical properties as compared with those of RHB1 and RHB3.

Synthesis of 3H‐Pyrrolo‐(1,2‐a) Indole‐based Fluorophore Macrocycles and their Stable Cation Radicals

“…[5] Ideal fluorophores for sensitive signaling applications at low concentrations must exhibit high fluorescence quantum yields and singlet state lifetimes. Multiple small molecular aromatic systems such as pyrene, [6,7] perylene, [8][9][10] coumarin (I), [11][12][13] fluorescein (II), [14][15][16][17] rhodamine (III), [18][19][20] BODIPY (IV), [21][22][23][24][25] and their analogs whose reduced degrees of freedom suppress nonradiative singlet excited state deactivation modes, exhibit good quantum yields and singlet state lifetimes. These small fluorescent molecules are important both as labeling agents and activatable sensors.…”

Rhodamine B Amide Derivatives with Anticancer Activity and Fluorescence Properties for Potential Theranostic Applications

“…Hence, a positive solvatokinetic effect might be the possible cognition for the reduction in fluorescence quantum yield with an increase in solvent polarity. [6] Coherent to the above concept, we expect lower quantum yields in polar (Hbonding) solvents like H 2 O, MeOH, EtOH, and n-PrOH. But, Φ f values were observed from ~0.1-0.98 in the above solvents indicating the imperceptible effect of H-bonding on Φ f values.…”

“…[5] RHB can be employed for bioimaging and as a biosensor. [6] Moreover, it doesn't have a cytotoxic effect. [7] RHB derivatives basically exist in two forms i. e., open chain form (highly fluorescent, pink) and spirocyclic form (nonfluorescent, colorless).…”

“…Several research groups have been engaged in developing conjugated rhodamine-related organic molecules over the last decade. [6,13] Solid-phase chemistry for efficient synthesis of Nalkylated rhodamine amide derivatives developed by Brulikova et al exhibited high photostability, pH-independent features, and practical utility as sensors in a biological application. [14] Csuk et al reported the cytotoxic effects of ester and amide derivatives of RHB on different human tumor cell lines which revealed lesser EC 50 values as low as 0.23 and 0.15 μM for ethyl and hexyl ester, against MCF-7 tumor cells, with lack of selectivity; alternatively morpholinyl derived RHB amide showed good selectivity, but not as cytotoxic as RHB ester, i. e., EC 50 is 0.44-3.76 μM for MCF-7 breast adenocarcinoma cells, furthermore could not explain the selectivity behavior of simple morpholinyl compounds in contrast to the complex triterpenoids.…”

“…Amidst xanthene dyes, rhodamine B (RHB) and its derivatives played a key role as multipurpose functional dyes, due to their excellent spectral characteristics and tool for studying more complex biochemical processes and activities [5] . RHB can be employed for bioimaging and as a biosensor [6] . Moreover, it doesn't have a cytotoxic effect [7] .…”