РОДАМИНБГИДРАЗИД

Description

Rhodamine B hydrazide is a spirolactam derivative of the rhodamine B dye, a basic platform for the construction of fluorescent chemosensors for metal cations. Systematic name: spiro[1H-isoindole-1,9'-[9H]xanthene]-3(2H)-one, 2-amino-3',6'-bis(diethylamino)-. Formula C28H32N4O2. In the closed spirolactam form, the compound is colorless and does not fluoresce; opening of the cycle gives an intense pink color and strong fluorescence. The entire class of rhodamine probes is based on this transition, which is why the substance is found in catalogs under the name “rhodamine B Cu2+ sensor.”

Basic Attributes

• CAS No: 74317-53-6
• Chemical formula: C28H32N4O2
• Molecular Weight: 456.58
• Exact weight: 456.25252628
• DSSTox ID: DTXSID40400828

Physico-chemical characteristics

• Density: 1.27±0.1 g/cm³
• Melting point: 176–177 °C
• Boiling point: 643.3±65.0 °C (predicted)
• pKa: 6.44±0.20

Operating principle

The xanthene core of rhodamine in the hydrazide form is locked into a five-membered spirolactam. The conjugation is broken, there is no absorption in the visible region, and the fluorescence is extinguished. Upon binding of a metal cation or upon protonation, the lactam ring opens, the flat quinoid structure of the dye is restored, and the solution changes from colorless to pink or rose-red with bright orange-red fluorescence. The response is recorded in two ways at once - colorimetrically by eye and fluorimetrically, which gives a two-channel probe.

Scope of application

• starting compound for the synthesis of chemosensors: condensation of the hydrazide group with aldehydes and ketones gives acylhydrazones with a given selectivity to the cation
• definition of Cu²⁺: derivative with 2,3,4-trihydroxybenzaldehyde gives a colorless to pink transition visible to the naked eye
• Determination of Fe³⁺: probes of this series operate as a “turn-on” type with orange fluorescence; they were used to visualize ions in HeLa cells and zebrafish
• determination of Hg²⁺: the two-channel sensor in an aqueous medium gives a pink-red transition with a detection limit of about 6.09 × 10⁻⁷ mol/l
• determination of Pd²⁺, Co²⁺, Al³⁺ - based on the same spirolactam mechanism
• test strips on filter paper for field express analysis
• forensics: investigated as a fluorescent reagent for the development of latent fingerprints

Hazard classification

• Hazard Statement: H302 (100%) - Harmful if swallowed [acute toxicity, oral route]. Aggregated data from the ECHA C&L Register - 38 companies, 1 notification. Signal word "Danger"
• Precautions: P261, P264, P270, P271, P280, P301 + P312, P302 + P352, P304 + P340, P305 + P351 + P338, P310, P312, P321, P330, P332 + P313, P362, P403 + P233, P405, P501
• Hazard class code: 22-37/38-41
• Safety instructions: 26-36
• Tags: Xn
• WGK Germany: 3

Storage and handling

Tightly closed container, cool, dry place, protected from light: rhodamine derivatives fade under light. Code 41 indicates a risk of serious eye damage - working with closed glasses is required, instruction 26 requires immediate copious rinsing with water if it gets into the eyes and seek medical attention. Code 37/38 - irritation of the respiratory tract and skin, hence working under traction and wearing gloves. Water hazard class 3: solutions, rinsing waters and dye residues are collected separately, discharge into the sewer is excluded.