Threepart table footnotes with brackets

Question

Currently the threeparttable displays the footnotes and references to footnotes as showed in following picture.

How can I configure treeparttable to display the reference to the footnote with [a], [b] and [c] and list it under the footnote section with "[a] Note one", "[b] Note one" and so on?

PS: I would like to keep the references in the table and the footnote section superscript (but I do not know how to write superscript with StackExchange syntax).

Answer 1

(rewrote the answer to focus on modifying the \tnote macro)

Quoting from page 1 of the user guide of the threeparttable package:

There is nothing automatic about the notes.

For your use case, though, obtaining the desired formatting, viz., surrounding the arguments of \tnote to be surrounded by square brackets automatically, is actually not too difficult, since it "only" requires hacking the \tnote macro itself. The package's definition of \tnote is as follows:

\def\tnote#1{\protect\TPToverlap{\textsuperscript{\TPTtagStyle{#1}}}}

To obtain your desired format, overwrite it via

\def\tnote#1{\protect\TPToverlap{\textsuperscript{[\TPTtagStyle{#1}]}}}

Can you spot the difference?

\documentclass{article}

\usepackage[para,flushleft]{threeparttable}
\def\tnote#1{\protect\TPToverlap{\textsuperscript{[\TPTtagStyle{#1}]}}}

\usepackage{booktabs,array}
\begin{document}

\begin{table}
\sffamily % optional
\centering
\begin{threeparttable}
\caption{Solvent screening}
\begin{tabular}{@{} *{3}{w{l}{1in}} @{}}
   \toprule
   entry\tnote{a} & ee\tnote{b} & conv.\tnote{c} \\
   \bottomrule
\end{tabular}
\smallskip
\footnotesize
\begin{tablenotes}
   \item[a] Note one   \item[b] Note two   \item[c] Note three
\end{tablenotes}
\end{threeparttable}
\end{table}

\end{document}