## 2 Materials and Methods
### Synthesis  
Scheme 1 highlights the synthetic steps used to make dye Family 2. Starting from **3a**[54] (Scheme 1A), bromination with 2 equivalents of N-bromosuccinimide (NBS) yielded compound **4**. Careful attention was given to the stoichiometry of NBS, as over-bromination yielded an observed side product. Molecule **4** was then converted to the ferrocene derivatives **3b** and **3c** using a Suzuki cross-coupling with ferrocene boronic acid.  
**Scheme 1. Part (A): the synthesis of Fc-TPA dyes **2b** and **2c** using Suzuki cross-coupling. **2a** and **3a** were previously reported [54]. Part (**B**): the synthesis of Fc-alkyne-TPA dyes **2d** and **2e** using Sonogashira/Suzuki cross-coupling strategies.  
It should be stressed that there are few examples of TPA-ferrocene compounds in the literature, and we think we know why. The cross-coupling (both Sonogashira and Suzuki) with ferrocene and TPA is very challenging; it took several efforts by former students before we landed on a successful reaction condition that yielded the desired product. In our hands, the need for a phase transfer catalyst (tetrabutylammonium tetrafluoroborate), toluene/water, and specifically potassium carbonate were extremely important for the success of the reaction. In addition, the Pd(dppf)Cl\({}_{2}\) catalyst seemed to be another piece needed to carry out these reactions. In the case of **3b** and **3c**, stoichiometry was also carefully controlled, but mixtures of di-ferrocenyl (**3c**) and dibromide (**3b**) were found in the product distribution of each reaction regardless. The partial cross-coupling is believed to be a result of the highly electron-rich TPA (and Fc-modified TPA) having a lower rate of oxidative addition with respect to the aryl halide. As a result of incomplete cross-coupling, careful chromatography was needed to isolate the desired compound. After achieving this, **3b** and **3c** were reacted further using a Knoevenagel condensation with cyanoacetic acid to yield compounds **2b** and **2c**, respectively.  
The syntheses of **2d** and **2e** were done using a combination of Suzuki and Sonogashira cross-coupling reactions. **5d** and **5e** were prepared similarly to each other after Sonogashira coupling of ethynyl-ferrocene [55] with tribromotriphenylamine using varied stoichiometry and careful chromatography. **5d** and **5e** were then cross-coupled with boronic ester (**6**[56]) to yield **3d** and **3e**, respectively. Again, both **3d** and **3e** underwent a Knoevenagel condensation with cyanoacetic acid to yield compounds **2d** and **2e**, respectively.  
We were quite surprised that prior to this work, TPA-alkylpyrrolerrocene derivatives **5d** and **5e** had not been previously reported. After working with these compounds, we have discovered why. Ferrocene-alkyne-TPA (all of our d and e) derivatives are not particularly stable in solution. Chromatography was our principal route for purification, but there was regular attrition in yield because samples needed to be frequently recrystallized. In addition, we needed to use ascorbic acid washes during extractions. All these steps were critical for our physicochemical and structural characterization. While it is not surprising to see electron-rich alkynes undergoing several side reactions including alkyne hydroalkoxylation and benzannulation, we did begin to question their utility in materials chemistry applications after handling these dyes and precursors.