NIR-II Fluorescent Small Molecule via D-π-A Segmentation

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Solution Overview

Problem

Existing near-infrared region II fluorescent small molecules face challenges such as complex synthesis processes, instability, low fluorescence quantum yield, and toxicity, limiting their practical application in biomedicine.

Innovation Solution

A near-infrared region II fluorescent small molecule is developed using a D-π-A system structure, incorporating a naphthalimide salt as a strong electron acceptor, dioxythiophene as a π bridge, and an N, N-dimethylstyrene structure as an electron donor, simplifying synthesis, enhancing stability, and improving fluorescence quantum yield.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If benzobisthiadiazole structure is used as main body, then fluorescence quantum yield is high, but synthesis process becomes cumbersome and toxicity increases

Engineering Contradiction:

Improvefluorescence quantum yieldVSAvoidsynthesis process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The molecule is divided into three functional modules: electron donor (N,N-dimethylstyrene), π bridge (dioxythiophene), and electron acceptor (naphthalimide salt). This segmentation allows independent optimization of each module's properties and simplifies the overall synthesis process by using standardized coupling reactions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the molecular structure parameters by selecting specific compounds with desirable properties: N,N-dimethylstyrene for electron donation, dioxythiophene for π-conjugation and stability, and naphthalimide salt for strong electron acceptance. This parameter optimization achieves high fluorescence quantum yield while simplifying synthesis.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If polymethyl as main body is used, then synthesis is simplified, but stability decreases and quantum yield becomes low

Engineering Contradiction:

Improvesynthesis simplicityVSAvoidchemical stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a composite molecular structure combining three different functional units: electron donor, π bridge, and electron acceptor. This composite approach achieves both synthesis simplicity and high stability by leveraging the advantageous properties of each component.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Instead of using conventional polymethyl structures, the patent inverts the approach by using a discrete small molecule with a carefully designed D-π-A system. This inversion leads to improved stability and quantum yield while maintaining synthesis simplicity.

Inventive Principle:

Principle #13The other way round (Inversion)

3Illumination intensity

If cyanine dye is used, then fluorescence tailing occurs at 1000-1200 nm, but fluorescence quantum yield becomes extremely low and instrument requirements increase

Engineering Contradiction:

Improvefluorescence wavelength rangeVSAvoidfluorescence quantum yield

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent applies local quality by optimizing specific regions of the molecular structure: the naphthalimide salt provides strong electron acceptance at the acceptor end, while the dioxythiophene π bridge provides localized conjugation. This localized optimization achieves high fluorescence quantum yield in the NIR-II region without requiring extreme instrument specifications.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The resulting fluorescent small molecule exhibits a simple synthesis process, stable chemical structure, high fluorescence quantum yield, and human safety, with potential applications in tumor surgery navigation imaging and medical cell labeling.

Implementation Method 1

a near-infrared region II fluorescent small molecule with a D-π-A system structure is constructed by using a naphthalimide salt as a strong electron acceptor, dioxythiophene as a π bridge and an N, N-dimethylstyrene structure as an electron donor

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 2

a dioxythiophene heterocycle is prone to stabilizing the structure of the small molecule

Methodology Applied

Scientific EffectMolecular orbital stabilization:

Implementation Method 3

The structure of the naphthalimide salt F1 is as follows: the bromine group for electron donor is prone to further modifying a probe

Methodology Applied

Scientific EffectElectron donation:

Data Source

PatentUS12275743B2Method for preparing near-infrared region II fluorescent small molecule

Publication Date: 2025.04.15 NANJING NUOYUAN MEDICAL DEVICES CO LTD

AI summary

The present disclosure provides a method for preparing a near-infrared region II fluorescent small molecule. The method utilizes organic full synthesis to construct a novel structured fluorescent probe small molecule, belonging to the fields of chemical sensing technology and fluorescence imaging. Compared with the currently studied fluorescent probe with a benzobisthiadiazole structure, the near-infrared region II fluorescent small molecule has the advantages of simple synthesis method, easy modification, stable structure, high fluorescence quantum yield and the like.