Molecules Formatting Requirements: Complete Author Guide

Molecules follows MDPI's standardized abstract format across all its journals.

• Word limit: About 200 words maximum

• Structure: Single paragraph in the style of a structured abstract (background, methods, results, conclusion), without headings

• Citations: No reference to the bibliography or figures; citations to published papers are not required in abstracts

• Abbreviations: Define at first use in the abstract

• Mathematical formulas: Equations are not to be included in the abstract

• Keywords: 3 to 10 keywords required, listed immediately below the abstract

MDPI words the limit as "about 200 words maximum," so treat 200 words as the ceiling. The technical pre-check tests adherence to the Instructions for Authors, so an over-length abstract is an avoidable problem.

Molecules covers organic chemistry, medicinal chemistry, natural products, food chemistry, and materials chemistry. Because the readership is broad, your abstract needs to be accessible to chemists outside your specific niche. Don't assume the reader knows your model compound or your assay by name. State what you did and what you found in concrete terms.

MDPI journals display the abstract prominently on the article page, and it's the primary text that appears in Google Scholar results. Spending an extra 30 minutes on a sharp abstract has a real impact on readership.

Molecules follows the standard MDPI figure guidelines.

Figure specifications:

Table formatting:

• Tables must be editable (not images)

• Created using Word's table function or LaTeX table environments

• Number sequentially (Table 1, Table 2, etc.)

• Title goes above the table

• A table footnote below the table can explain material referring to the whole table or to specific entries

• Vertical lines, blank rows and blank columns are not advised

One area where Molecules stands out from most publishers: there's no charge for color figures. This is standard across MDPI journals, and it means you don't need to design figures that work in both color and grayscale. Use color strategically for clarity, not just decoration.

Chemical structures and reaction schemes should be drawn with software designed for the purpose, such as ChemDraw, ChemSketch, ISIS/Draw or ChemWindow, at a scale where all details and text are clearly legible (text no smaller than 8 to 9 pt, per the Molecules instructions). Physical and spectroscopic data, and tables of NMR data, should follow the ACS Preparation and Submission of Manuscripts standard.

Schemes (reaction schemes) are numbered separately from figures. Use Scheme 1, Scheme 2, etc. This is important because the Molecules instructions number figures, schemes and tables in order of appearance with their own labels (Figure 1, Scheme 1, Figure 2, Scheme 2, Table 1).

Molecules uses the MDPI reference style, a numbered style in which journal titles are abbreviated by the ISO 4 rules and the full article title is given.

In-text citations: Numbers in square brackets, e.g., [1], [2,3], [4-7]. Numbered in order of first appearance.

Reference list format:

1. Author, A.B.; Author, C.D. Title of Article. Abbreviated Journal Name Year, Volume, Page Range.

Key formatting details:

• Author names: Surname, followed by initials with periods (e.g., "Smith, J.K.")

• Semicolons between authors

• Abbreviate journal titles by the ISO 4 rules (e.g., "J. Am. Chem. Soc." rather than "Journal of the American Chemical Society"); if you are unsure how to abbreviate a title, leave the full title and the Editorial Office will abbreviate it

• Year, then volume, then page range, as in the MDPI example

• DOI numbers are not mandatory but are highly encouraged

Authors who've published at Elsevier, Wiley, ACS, or RSC journals are used to ISO 4 abbreviations, and MDPI uses them too. If you use a reference manager, set it to the MDPI output style, which handles this automatically. MDPI provides style files for EndNote and Zotero.

MDPI publishes no reference cap for Molecules.

MDPI handles supplementary material differently from most traditional publishers.

What goes in supplementary material:

• Additional experimental data (spectra, chromatograms, additional assay results)

• Extended tables that would break the flow of the main text

• Computational data (coordinates, input files)

• Video content

• Datasets

Formatting requirements:

• Any file format is accepted, but MDPI recommends common, non-proprietary formats; number the items with the S prefix (Figure S1, Table S1, etc.)

• If Excel files or datasets are needed, they can be submitted as separate files

• Each supplementary item must be cited in the main text

• Supplementary files are peer-reviewed alongside the main manuscript

MDPI publishes all supplementary material as open-access alongside the article on the journal website. There are no access barriers, which is worth knowing if your supplementary material contains data you want freely accessible.

A note about NMR spectra: Molecules frequently publishes synthetic chemistry work, and reviewers routinely ask for NMR spectra in the supplementary material for all new compounds. If you're reporting previously undescribed organic compounds, include the 1H, 13C and/or other key NMR spectra together with HRMS or elemental analysis in the supplementary file from the start, as the Molecules instructions ask. Adding them later costs you a revision cycle.

These are the details specific to Molecules that aren't obvious from a quick read of the author guidelines:

MDPI uses its own in-house production workflow. MDPI's in-house teams perform production on all manuscripts, including language editing, copy editing, and conversion to XML. The Molecules instructions say using the template file substantially shortens copy-editing and publication, which is why the template is encouraged.

Graphical abstract is optional but displayed prominently. If you provide a graphical abstract, it appears beneath the text abstract on the online version of the article, and it is typically absent from the print version or article PDF. The minimum required size is 560 × 1100 pixels (height × width), in PNG, JPEG or TIFF format.

Author names and affiliations follow a set format. Authors' full first and last names must be provided, and affiliations use the PubMed/MEDLINE standard format with complete address information (city, zip code, state or province, and country). At least one author should be designated as the corresponding author. Authors who contributed equally are marked with a superscript symbol (†) below the affiliations. ORCID iDs are strongly recommended and can be added in the submission system.

Molecules has an open peer review option. Authors can choose to have their reviewer reports published alongside the paper. This doesn't affect formatting, but it does affect how you write your cover letter and response to reviewers, since those might become public.

Data availability statement is mandatory. Every Molecules paper must include a Data Availability Statement at the end of the manuscript (before the references). Choose from standard MDPI templates: data available in the article, data available on request, no new data created, or data available in a public repository.

Funding and acknowledgments are formatted sections. The MDPI template includes dedicated sections for Funding and Acknowledgments with specific formatting. Don't merge these into a single paragraph at the end of the paper. They need to be separate, labeled sections.

Based on common revision requests at Molecules:

1. Journal title abbreviations in references. MDPI asks for journal titles abbreviated by the ISO 4 rules; if you are unsure how to abbreviate a title, leave the full title and the Editorial Office will abbreviate it.

1. Missing ORCID iDs. MDPI strongly recommends that authors have an ORCID account. The ORCID can be added in the submission system and is shown with an icon in the published paper.

1. Scheme vs Figure numbering. Reaction schemes must be numbered separately from figures (Scheme 1, Scheme 2).

1. Section numbering conflicts. If you manually number sections and also use the template's auto-numbering, you'll get double numbers (e.g., "3.3. Results").

1. Supplementary material not cited in text. Every supplementary figure and table must be referenced at least once in the main text.

For manuscripts targeting Molecules, four patterns generate the most consistent desk-rejection outcomes.

Required sections missing or the MDPI template ignored. Molecules encourages the official MDPI Word or LaTeX template and accepts free-format submission, so a different layout is not itself a reason for return. The technical pre-check does test adherence to the Instructions for Authors, and a free-format manuscript must still contain every required section: author information, abstract, keywords, introduction, materials and methods, results, conclusions, figures and tables with captions, funding information, author contributions, and conflict of interest and other ethics statements. At the revision stage you are asked to format the manuscript to the journal guidelines.

Abstract exceeds about 200 words or is not self-contained. The Molecules instructions ask for a single-paragraph abstract of about 200 words maximum, in the style of a structured abstract but without headings, and the MDPI Layout Style Guide asks for a self-contained abstract: abbreviations defined in it, no reference to the bibliography or figures, and no equations, tables or website links. The abstract must stand alone as a complete summary covering background, methods, key results, and conclusions.

Journal titles not abbreviated the MDPI way. Molecules follows the MDPI reference style, which abbreviates journal titles by the ISO 4 rules and gives the full article title. The MDPI reference guide's own example abbreviates a journal as "Am. J. Clin. Nutr."; if you are unsure how to abbreviate a title, leave the full title and the Editorial Office will abbreviate it. Authors who export references from a reference manager should switch it to the MDPI output style.

Supplementary Materials not cited in the manuscript. Additional data and files can be uploaded as Supplementary Files during submission, and MDPI's Layout Style Guide requires that Supplementary Materials be mentioned in the main text and numbered with the S prefix (Figure S1, Table S1). Supplementary items that are never cited, or that are cited without a corresponding file, are an avoidable problem.

A Molecules submission readiness check evaluates manuscript structure, MDPI template compliance, abstract length, and reference format against these desk-rejection patterns before you submit.

For a manuscript-specific signal before you submit, run a Molecules submission readiness check.

Or see example reports before you finalize.