我們應用了不同Crown ether與不同離子的結合具有選擇性，並結合Rhodamine spirolactam分子結構中的化學螢光開關，開發了四種不同的N-(Rhodamine-6G)lactam，而中間連接的碳鏈與crown ether的化學環境是相似的。並在作為Fe3+、Cr3+的化學感測器上，其選擇性跟靈敏性都具有不錯的結果。其中間連結的碳鏈，它所包含的氧原子數目，須為五到六個，才能形成最佳化的腔位來容納離子，進而感測到它們。

Among the fluorophores developed, xanthenes, including rhodamines and fluoresceins, are highly favorable because of their excellent photophysical properties, such as high extinction coefficients, excellent quantum yields, great photostability, and relatively long emission wavelengths.

However, it was only in 1997 that the rhodamine derivative and its ring-opening reaction received a great deal of attention from organic chemists Rhodamine spirolactam or spirolactone derivatives are nonfluorescent and colorless, whereas ring-opening of the corresponding spirolactam/lactone gives rise to strong fluorescence emission and a pink color. In general, rhodamine derivative displays a red color change and strong fluorescence in acidic solutions by activation of a carbonyl group in a spirolactone or spirolactam moiety. In a similar way, an appropriate ligand on a spirolactam ring can induce a color change as well as a fluorescence change upon addition of metal ions, even though this his process is somewhat dependent on the solvent system.

The development of fluorescent chemical devices is a promising field. An important area within this field is the design of fluorescent chemosensors for various metal ions. Ions play a fundamental role in a wide range of chemical and biological processes, and numerous efforts have been made in the development of effective fluorescent chemosensors. Sensors based on ion-induced changes in fluorescence appear to be particularly attractive due to their simplicity, high sensitivity, and instantaneous response.

The trivalent form of iron is an essential element in man. It provides the oxygen-carrying capacity of heme and acts as a cofactor in many enzymatic reactions involved in the mitochondrial respiratory chain. Meanwhile, the trivalent form of chromium is also an essential nutrient for humans, and its deficiency causes disturbances in the glucose levels and lipid metabolism. On the other hand, chromium is an environmental pollutant, and its build-up due to various industrial and agricultural activities is a matter of concern. The Fe(III) ion in the structure of many enzymes is involved as a catalyst for oxyen metabolism and electron transfer mechanisms in the human body. However, a high concentration of Fe(III) ions has a toxic effect on living organisms and causes diseases such as Parkinson’s disease and Alzheimer’s disease.

In addition, the ferric ion is famous as a fluorescence quencher due to its paramagnetic nature, and most of the reported Fe(III) receptors, such as analogues of ferrichromes or siderophores, undergo a fluorescence quenching when bound with Fe(III), though it is generally believed that probes with a fluorescence enhancement signal when interacting with analytes are much more efficient. Therefore, the development of new fluorescent Fe(III) indicators, especially those that exhibit selective Fe(III)-amplified emission, is still a challenge.

Different crown ether type of metal ions on their good complexing ability, crown ether by itself atomic oxygen lone pair of electrons gripping metal ions. Molecular recognition is the specific binding of a guest molecule to a complementary host molecule to form a host-guest complex .

We use the combination of different Crown ether having different ion selectivity and binding of the molecular structure of Rhodamine spirolactam Chemiluminescent switch developed four different N-(Rhodamine-6G) lactam(CHEF-OFF-ON), and the carbon chain of the intermediate connection crown ether is a similar chemical environment

We also did the conceptual design of molecules not only that, we also added a fluorescent chemical sensors into a common concept- Excimer Formation, it belongs to a union-type fluorescent chemical sensor. Synthesis of both sides of the N-(Rhodamine-6G) is in order to form excimer, because it is only to the end of the lactam to chelate metal ions, then, after the end of one side or both sides of the amine group amine with Rhodamine-6G response to chelate metal ions make lactam talk it is open-loop, one or both sides are pretty much the same result. Finally, we expect the molecule can form excimer, metal ions in the catch, while both sides of the N-(Rhodamine-6G) lactam will π-π stacking interaction phenomena, accompanied by red shift produced felt able to judge whether the measured molecular ions.

After determining the product of the iron ions are chromium ions with a good selectivity with sensitivity , we calculate the product of the ion binding constants, like the chemical environment found in the middle of a carbon chain crown ether capacity sensed ions are close relationship.

Therefore, we conclude that in the middle of the carbon chain, and crown ether to produce a similar chemical force, the production process and the ion sensing.Bonding mode is not just a simple chemical switch is triggered at the end of it. And wherein the number of oxygen atoms must be five or six in the case, in order to optimize the formation of a cavity-like structure to hold the ions, and thus ions can be sensed.

Summary, we combine the concept of different ions of different Crown ether specific binding force, and the N-(Rhodamine-6G) lactam chemical structure fluorescent switch principle, successfully developed a new type of fluorescent chemical sensor

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